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:heavy_check_mark: test/library-checker/system_of_linear_equations.test.cpp

Depends on

Code

#define PROBLEM "https://judge.yosupo.jp/problem/system_of_linear_equations"

#include "src/algebra/linear/lu.hpp"
#include "src/algebra/modint.hpp"
#include "src/utils/io/istream.hpp"
#include "src/utils/io/ostream.hpp"

namespace workspace {

using mint = modint<998244353>;
using mat = matrix<mint>;

void main() {
  // start here!

  size_t n, m;
  cin >> n >> m;

  lu_decomposition lu = [&] {
    mat a(n, m);
    cin >> a;
    return a;
  }();

  auto res = lu.solve([&] {
    std::vector<mint> b(n);
    cin >> b;
    return b;
  }());

  if (!res.first) {
    std::cout << "-1\n";
    return;
  }

  auto ker = lu.kernel();
  std::cout << ker.size() << "\n" << res.second << "\n";
  for (auto &&v : ker) std::cout << v << "\n";
}

}  // namespace workspace

int main() { workspace::main(); }
#line 1 "test/library-checker/system_of_linear_equations.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/system_of_linear_equations"

#line 2 "src/algebra/linear/lu.hpp"

/**
 * @file lu.hpp
 * @brief LU decomposition
 */

#include <numeric>

#line 2 "src/algebra/linear/matrix.hpp"

/**
 * @file matrix.hpp
 * @brief Matrix
 * @date 2021-02-15
 *
 *
 */

#include <cassert>
#include <valarray>

namespace workspace {

/**
 * @brief Fixed size matrix.
 *
 * @tparam _Scalar
 * @tparam _Rows Number of rows
 * @tparam _Cols Number of columns
 */
template <class _Scalar, std::size_t _Rows = 0, std::size_t _Cols = _Rows>
class matrix {
 public:
  _Scalar __data[_Rows][_Cols] = {};

  using value_type = _Scalar;
  using size_type = std::size_t;

  constexpr static matrix eye() {
    static_assert(_Rows == _Cols);

    matrix __e;
    for (size_type __d = 0; __d != _Rows; ++__d) __e.__data[__d][__d] = 1;
    return __e;
  }

  constexpr operator decltype((__data))() { return __data; }
  constexpr operator decltype(std::declval<const matrix>().__data)
      const&() const {
    return __data;
  }

  constexpr auto begin() { return __data; }
  constexpr auto begin() const { return __data; }

  constexpr auto end() { return __data + _Rows; }
  constexpr auto end() const { return __data + _Rows; }

  constexpr size_type rows() const { return _Rows; }

  constexpr size_type cols() const { return _Cols; }

  constexpr auto transpose() const {
    matrix<_Scalar, _Cols, _Rows> __t;

    for (size_type __r = 0; __r != _Rows; ++__r)
      for (size_type __c = 0; __c != _Cols; ++__c)
        __t.__data[__c][__r] = __data[__r][__c];

    return __t;
  }

  constexpr matrix operator+() const { return *this; }

  constexpr matrix operator-() const {
    matrix __cp = *this;

    for (auto& __v : __cp.__data)
      for (auto& __e : __v) __e = -__e;

    return __cp;
  }

  template <class _Matrix> constexpr matrix& operator+=(const _Matrix& __x) {
    auto __m = std::min(_Rows, __x.rows());
    auto __n = std::min(_Cols, __x.cols());

    for (size_type __r = 0; __r != __m; ++__r)
      for (size_type __c = 0; __c != __n; ++__c)
        __data[__r][__c] += __x[__r][__c];

    return *this;
  }

  template <class _Matrix>
  constexpr matrix operator+(const _Matrix& __x) const {
    return matrix(*this) += __x;
  }

  template <class _Matrix> constexpr matrix& operator-=(const _Matrix& __x) {
    auto __m = std::min(_Rows, __x.rows());
    auto __n = std::min(_Cols, __x.cols());

    for (size_type __r = 0; __r != __m; ++__r)
      for (size_type __c = 0; __c != __n; ++__c)
        __data[__r][__c] -= __x[__r][__c];

    return *this;
  }

  template <class _Matrix>
  constexpr matrix operator-(const _Matrix& __x) const {
    return matrix(*this) -= __x;
  }

  template <class _Scalar2>
  constexpr matrix& operator*=(const matrix<_Scalar2, _Cols, _Cols>& __x) {
    if (this == &__x) return operator=(operator*(__x));

    for (auto& __r : __data) {
      _Scalar __tmp[_Cols] = {};

      auto __v = *__x.__data;
      for (auto& __w : __tmp) {
        auto __i = __v++;
        for (const auto& __e : __r) __w += __e * *__i, __i += _Cols;
      }

      auto __w = __tmp;
      for (auto& __e : __r) __e = std::move(*__w++);
    }

    return *this;
  }

  template <class _Scalar2, size_type _Rows2, size_type _Cols2>
  constexpr auto operator*(const matrix<_Scalar2, _Rows2, _Cols2>& __x) const {
    matrix<typename std::common_type<_Scalar, _Scalar2>::type, _Rows, _Cols2>
        __m;

    auto __w = *__m.__data;
    for (const auto& __r : __data)
      for (auto __v = *__x.__data, __v_end = __v + _Cols2; __v != __v_end;
           ++__w) {
        auto __i = __v++;
        for (auto __e = __r; __e != __r + std::min(_Cols, _Rows2); ++__e)
          *__w += *__e * *__i, __i += _Cols2;
      }

    return __m;
  }

  template <class _Matrix>
  constexpr
      typename std::enable_if<!std::is_convertible<_Matrix, value_type>::value,
                              matrix<_Scalar>>::type
      operator*(const _Matrix& __x) const {
    matrix<_Scalar> __m(_Rows, __x.cols());

    for (size_type __r = 0; __r != _Rows; ++__r)
      for (size_type __i = 0; __i != __x.cols(); ++__i)
        for (size_type __c = 0; __c != std::min(_Cols, __x.rows()); ++__c)
          __m[__r][__i] += __data[__r][__c] * __x[__c][__i];

    return __m;
  }

  constexpr matrix& operator*=(const value_type& __x) {
    for (auto& __v : __data)
      for (auto& __e : __v) __e *= __x;

    return *this;
  }

  constexpr matrix operator*(const value_type& __x) const {
    return matrix(*this) *= __x;
  }

  constexpr matrix& operator/=(const value_type& __x) {
    assert(__x != value_type(0));

    for (auto& __v : __data)
      for (auto& __e : __v) __e /= __x;

    return *this;
  }

  constexpr matrix operator/(const value_type& __x) const {
    return matrix(*this) /= __x;
  }

  template <class _Int> constexpr matrix pow(_Int __e) const {
    assert(0 <= __e);

    matrix __m = eye();
    for (matrix __cp = *this; __e; __cp *= __cp, __e >>= 1)
      if (__e & 1) __m *= __cp;

    return __m;
  }

  template <class _Os>
  constexpr friend _Os& operator<<(_Os& __os, const matrix& __x) {
    for (auto __i = __x.begin(); __i != __x.end(); ++__i, __os << '\n')
      for (size_type __c = 0; __c != _Cols; ++__c)
        __c ? void(__os << ' ') : (void)0, __os << *(*__i + __c);

    return __os;
  }
};  // namespace workspace

/**
 * @brief Dynamic matrix.
 *
 * @tparam _Scalar
 * @tparam _Rows Number of rows
 * @tparam _Cols Number of columns
 */
template <class _Scalar>
class matrix<_Scalar, 0, 0> : public std::valarray<std::valarray<_Scalar>> {
  using base = std::valarray<std::valarray<_Scalar>>;
  using row_type = typename base::value_type;

 public:
  using value_type = _Scalar;
  using size_type = std::size_t;

  using base::operator[];

  static matrix eye(size_type __n) {
    matrix __e(__n, __n);
    for (size_type __d = 0; __d != __n; ++__d) __e[__d][__d] = 1;
    return __e;
  }

  matrix() = default;

  matrix(size_type __n) : matrix(__n, __n) {}

  matrix(size_type __m, size_type __n) : base(row_type(__n), __m) {}

  template <class _Tp, typename = typename std::enable_if<
                           std::is_constructible<base, _Tp>::value &&
                           !std::is_constructible<size_type, _Tp>::value>::type>
  matrix(_Tp&& __x) : base(__x) {}

  matrix(std::initializer_list<row_type> __x) : base(__x) {}

  size_type rows() const { return base::size(); }

  size_type cols() const { return rows() ? operator[](0).size() : 0; }

  matrix transpose() const {
    matrix __t(cols(), rows());

    for (size_type __r = 0; __r != rows(); ++__r)
      for (size_type __c = 0; __c != cols(); ++__c)
        __t[__c][__r] = operator[](__r)[__c];

    return __t;
  }

  void resize(size_type __m, size_type __n) {
    matrix __t(__m, __n);

    if (rows() < __m) __m = rows();
    if (cols() < __n) __n = cols();

    for (size_type __r = 0; __r != __m; ++__r)
      for (size_type __c = 0; __c != __n; ++__c)
        __t[__r][__c] = std::move(operator[](__r)[__c]);

    base::swap(__t);
  }

  // binary operators {{

  template <class _Matrix, typename = void>
  struct is_valarray_based : std::false_type {};

  template <class _Matrix>
  struct is_valarray_based<
      _Matrix,
      typename std::enable_if<std::is_same<
          row_type, typename std::decay<decltype(
                        std::declval<_Matrix>()[0])>::type>::value>::type>
      : std::true_type {};

  template <class _Matrix>
  typename std::enable_if<!std::is_convertible<_Matrix, value_type>::value,
                          matrix&>::type
  operator*=(_Matrix&& __x) {
    return *this = operator*(std::forward<_Matrix>(__x));
  }

  template <class _Matrix>
  typename std::enable_if<!std::is_convertible<_Matrix, value_type>::value,
                          matrix>::type
  operator*(const _Matrix& __x) const {
    matrix __m(rows(), __x.cols());

    if constexpr (is_valarray_based<_Matrix>::value)
      for (size_type __r = 0; __r != rows(); ++__r)
        for (size_type __c = 0; __c != std::min(cols(), __x.rows()); ++__c)
          __m[__r] += operator[](__r)[__c] * __x[__c];

    else
      for (size_type __r = 0; __r != rows(); ++__r)
        for (size_type __i = 0; __i != __x.cols(); ++__i)
          for (size_type __c = 0; __c != std::min(cols(), __x.rows()); ++__c)
            __m[__r][__i] += operator[](__r)[__c] * __x[__c][__i];

    return __m;
  }

  matrix& operator*=(const value_type& __x) {
    for (size_type __r = 0; __r != rows(); ++__r)
      operator[](__r).operator*=(__x);

    return *this;
  }

  matrix operator*(const value_type& __x) const { return matrix(*this) *= __x; }

  friend matrix operator*(const value_type& __x, matrix __i) {
    for (size_type __r = 0; __r != __i.rows(); ++__r)
      __i.operator[](__r) = __x * __i.operator[](__r);

    return __i;
  }

  matrix& operator/=(const value_type& __x) {
    assert(__x != value_type(0));

    for (size_type __r = 0; __r != rows(); ++__r)
      operator[](__r).operator/=(__x);

    return *this;
  }

  matrix operator/(const value_type& __x) const { return matrix(*this) /= __x; }

  // }} binary operators

  template <class _Int> matrix pow(_Int __e) const {
    assert(0 <= __e);

    matrix __m = eye(rows());
    for (matrix __cp = *this; __e; __cp *= __cp, __e >>= 1)
      if (__e & 1) __m *= __cp;

    return __m;
  }

  // template <class _Is> friend _Is& operator>>(_Is& __is, matrix& __x) {
  //   for (size_type __r = 0; __r != __x.rows(); ++__r)
  //     for (size_type __c = 0; __c != __x.cols(); ++__c)
  //       __is >> __x.operator[](__r).operator[](__c);

  //   return __is;
  // }

  template <class _Os> friend _Os& operator<<(_Os& __os, const matrix& __x) {
    for (size_type __r = 0; __r != __x.rows(); ++__r, __os << '\n')
      for (size_type __c = 0; __c != __x.cols(); ++__c)
        __c ? void(__os << ' ') : (void)0,
            __os << __x.operator[](__r).operator[](__c);

    return __os;
  }
};

}  // namespace workspace
#line 11 "src/algebra/linear/lu.hpp"

namespace workspace {

template <class _Matrix> class lu_decomposition : public _Matrix {
 public:
  using value_type = typename _Matrix::value_type;
  using size_type = typename _Matrix::size_type;

  lu_decomposition() = default;
  lu_decomposition(const _Matrix &__x) : _Matrix(__x) { run(); }
  lu_decomposition(_Matrix &&__x) : _Matrix(std::move(__x)) { run(); }

 protected:
  std::vector<size_type> __perm, __pivots;
  bool sgn;

  void run() {
    __perm.resize(_Matrix::rows());
    std::iota(__perm.begin(), __perm.end(), 0);
    sgn = false;
    __pivots.clear();

    for (size_type __c = 0;
         __c != _Matrix::cols() && __pivots.size() != _Matrix::rows(); ++__c) {
      auto __max = (*this)[__pivots.size()][__c];
      auto __pos = __pivots.size();

      if constexpr (std::is_floating_point<
                        value_type>::value) {  // Find the biggest absolute
                                               // value in the column.
        for (size_type __r = __pivots.size() + 1; __r != _Matrix::rows(); ++__r)
          if (std::abs(__max) < std::abs((*this)[__r][__c]))
            __max = (*this)[__pos = __r][__c];
      }

      else if (__max ==
               static_cast<value_type>(
                   0))  // Find the first non-zero element in the column.
        for (size_type __r = __pivots.size() + 1; __r != _Matrix::rows(); ++__r)
          if ((__max = (*this)[__r][__c]) != static_cast<value_type>(0)) {
            __pos = __r;
            break;
          }

      if (__pos != __pivots.size()) {  // Swap 2 rows.
        sgn = !sgn;
        std::swap(__perm[__pos], __perm[__pivots.size()]);
        std::swap((*this)[__pos], (*this)[__pivots.size()]);
      }

      if (__max != static_cast<value_type>(0)) {  // Forward elimination
        for (size_type __r = __pivots.size() + 1; __r != _Matrix::rows();
             ++__r) {
          auto __m = (*this)[__r][__c] / __max;
          (*this)[__r][__c] = 0;
          (*this)[__r][__pivots.size()] = __m;

          for (size_type __i = __c + 1; __i != _Matrix::cols(); ++__i)
            (*this)[__r][__i] -= (*this)[__pivots.size()][__i] * __m;
        }

        __pivots.emplace_back(__c);
      }
    }
  }

 public:
  size_type rank() const { return __pivots.size(); }

  value_type det() const {
    assert(_Matrix::rows() == _Matrix::cols());

    value_type __d = sgn ? -1 : 1;
    for (size_type __i = 0; __i != _Matrix::rows(); ++__i)
      __d *= (*this)[__i][__i];
    return __d;
  }

  _Matrix lower() const;

  _Matrix upper() const;

  _Matrix inverse() const {
    assert(_Matrix::rows() == _Matrix::cols());

    _Matrix __inv;
    // add solve(e_i) to __inv for i=0, ..., rows()
    return __inv;
  }

  // O(dim(ker) * size)
  _Matrix kernel() const {
    _Matrix __ker(_Matrix::cols() - rank(), _Matrix::cols());

    for (size_type __c = 0, __i = 0; __c != _Matrix::cols(); ++__c) {
      if (__i != __pivots.size() && __pivots[__i] == __c) {
        ++__i;
        continue;
      }

      auto &__v = __ker[__c - __i];
      __v[__c] = 1;
      for (size_type __r = 0; __r != __i; ++__r) __v[__r] = -(*this)[__r][__c];

      for (size_type __j = __i; __j--;) {
        auto __x = __v[__j] / (*this)[__j][__pivots[__j]];
        __v[__j] = 0;
        __v[__pivots[__j]] = __x;

        for (size_type __r = 0; __r != __j; ++__r)
          __v[__r] -= (*this)[__r][__pivots[__j]] * __x;
      }
    }

    return __ker;
  }

  template <class _Vec> std::pair<bool, _Vec> solve(const _Vec &__b) const {
    assert(!(__b.size() < _Matrix::rows()));

    // Solution
    _Vec __y(_Matrix::rows()), __x(_Matrix::cols());

    // Backward substitution with L
    for (size_type __c = 0; __c != _Matrix::rows(); ++__c) {
      __y[__c] += __b[__perm[__c]];

      for (size_type __r = __c + 1; __r != _Matrix::rows(); ++__r)
        __y[__r] -= __y[__c] * (*this)[__r][__c];
    }

    // Backward substitution with U
    for (size_type __i = rank(); __i != _Matrix::rows(); ++__i)
      if (__y[__i] != static_cast<value_type>(0))
        return std::make_pair(false, __x);

    for (size_type __i = rank(); __i--;) {
      auto __c = __pivots[__i];

      __x[__c] = __y[__i] / (*this)[__i][__c];

      for (size_type __r = 0; __r != __i; ++__r)
        __y[__r] -= __x[__c] * (*this)[__r][__c];
    }

    return std::make_pair(true, __x);
  }
};

}  // namespace workspace
#line 2 "src/algebra/modint.hpp"

/**
 * @file modint.hpp
 * @brief Modular Arithmetic
 */

#line 9 "src/algebra/modint.hpp"
#include <iostream>
#include <vector>

#line 2 "src/number_theory/sqrt_mod.hpp"

/**
 * @file sqrt_mod.hpp
 * @brief Tonelli-Shanks Algorithm
 */

#line 2 "src/number_theory/pow_mod.hpp"

/**
 * @file mod_pow.hpp
 * @brief Modular Exponentiation
 */

#line 9 "src/number_theory/pow_mod.hpp"

#line 2 "src/utils/sfinae.hpp"

/**
 * @file sfinae.hpp
 * @brief SFINAE
 */

#include <cstdint>
#include <iterator>
#include <type_traits>

#ifndef __INT128_DEFINED__

#ifdef __SIZEOF_INT128__
#define __INT128_DEFINED__ 1
#else
#define __INT128_DEFINED__ 0
#endif

#endif

namespace std {

#if __INT128_DEFINED__

template <> struct make_signed<__uint128_t> { using type = __int128_t; };
template <> struct make_signed<__int128_t> { using type = __int128_t; };

template <> struct make_unsigned<__uint128_t> { using type = __uint128_t; };
template <> struct make_unsigned<__int128_t> { using type = __uint128_t; };

template <> struct is_signed<__uint128_t> : std::false_type {};
template <> struct is_signed<__int128_t> : std::true_type {};

template <> struct is_unsigned<__uint128_t> : std::true_type {};
template <> struct is_unsigned<__int128_t> : std::false_type {};

#endif

}  // namespace std

namespace workspace {

template <class Tp, class... Args> struct variadic_front { using type = Tp; };

template <class... Args> struct variadic_back;

template <class Tp> struct variadic_back<Tp> { using type = Tp; };

template <class Tp, class... Args> struct variadic_back<Tp, Args...> {
  using type = typename variadic_back<Args...>::type;
};

template <class type, template <class> class trait>
using enable_if_trait_type = typename std::enable_if<trait<type>::value>::type;

/**
 * @brief Return type of subscripting ( @c [] ) access.
 */
template <class _Tp>
using subscripted_type =
    typename std::decay<decltype(std::declval<_Tp&>()[0])>::type;

template <class Container>
using element_type = typename std::decay<decltype(*std::begin(
    std::declval<Container&>()))>::type;

template <class _Tp, class = void> struct has_begin : std::false_type {};

template <class _Tp>
struct has_begin<
    _Tp, std::__void_t<decltype(std::begin(std::declval<const _Tp&>()))>>
    : std::true_type {
  using type = decltype(std::begin(std::declval<const _Tp&>()));
};

template <class _Tp, class = void> struct has_size : std::false_type {};

template <class _Tp>
struct has_size<_Tp, std::__void_t<decltype(std::size(std::declval<_Tp>()))>>
    : std::true_type {};

template <class _Tp, class = void> struct has_resize : std::false_type {};

template <class _Tp>
struct has_resize<_Tp, std::__void_t<decltype(std::declval<_Tp>().resize(
                           std::declval<size_t>()))>> : std::true_type {};

template <class _Tp, class = void> struct has_mod : std::false_type {};

template <class _Tp>
struct has_mod<_Tp, std::__void_t<decltype(_Tp::mod)>> : std::true_type {};

template <class _Tp, class = void> struct is_integral_ext : std::false_type {};
template <class _Tp>
struct is_integral_ext<
    _Tp, typename std::enable_if<std::is_integral<_Tp>::value>::type>
    : std::true_type {};

#if __INT128_DEFINED__

template <> struct is_integral_ext<__int128_t> : std::true_type {};
template <> struct is_integral_ext<__uint128_t> : std::true_type {};

#endif

#if __cplusplus >= 201402

template <class _Tp>
constexpr static bool is_integral_ext_v = is_integral_ext<_Tp>::value;

#endif

template <typename _Tp, typename = void> struct multiplicable_uint {
  using type = uint_least32_t;
};
template <typename _Tp>
struct multiplicable_uint<
    _Tp,
    typename std::enable_if<(2 < sizeof(_Tp)) &&
                            (!__INT128_DEFINED__ || sizeof(_Tp) <= 4)>::type> {
  using type = uint_least64_t;
};

#if __INT128_DEFINED__

template <typename _Tp>
struct multiplicable_uint<_Tp,
                          typename std::enable_if<(4 < sizeof(_Tp))>::type> {
  using type = __uint128_t;
};

#endif

template <typename _Tp> struct multiplicable_int {
  using type =
      typename std::make_signed<typename multiplicable_uint<_Tp>::type>::type;
};

template <typename _Tp> struct multiplicable {
  using type = std::conditional_t<
      is_integral_ext<_Tp>::value,
      std::conditional_t<std::is_signed<_Tp>::value,
                         typename multiplicable_int<_Tp>::type,
                         typename multiplicable_uint<_Tp>::type>,
      _Tp>;
};

template <class> struct first_arg { using type = void; };

template <class _R, class _Tp, class... _Args>
struct first_arg<_R(_Tp, _Args...)> {
  using type = _Tp;
};

template <class _R, class _Tp, class... _Args>
struct first_arg<_R (*)(_Tp, _Args...)> {
  using type = _Tp;
};

template <class _G, class _R, class _Tp, class... _Args>
struct first_arg<_R (_G::*)(_Tp, _Args...)> {
  using type = _Tp;
};

template <class _G, class _R, class _Tp, class... _Args>
struct first_arg<_R (_G::*)(_Tp, _Args...) const> {
  using type = _Tp;
};

template <class _Tp, class = void> struct parse_compare : first_arg<_Tp> {};

template <class _Tp>
struct parse_compare<_Tp, std::__void_t<decltype(&_Tp::operator())>>
    : first_arg<decltype(&_Tp::operator())> {};

template <class _Container, class = void> struct get_dimension {
  static constexpr size_t value = 0;
};

template <class _Container>
struct get_dimension<_Container,
                     std::enable_if_t<has_begin<_Container>::value>> {
  static constexpr size_t value =
      1 + get_dimension<typename std::iterator_traits<
              typename has_begin<_Container>::type>::value_type>::value;
};

}  // namespace workspace
#line 11 "src/number_theory/pow_mod.hpp"

namespace workspace {

/**
 * @brief Compile time modular exponentiation.
 *
 * @param __x
 * @param __n Exponent
 * @param __mod Modulus
 * @return
 */
template <class _Tp>
constexpr std::enable_if_t<(is_integral_ext<_Tp>::value), _Tp> pow_mod(
    _Tp __x, _Tp __n, _Tp __mod) noexcept {
  assert(__mod > 0);

  using mul_type = typename multiplicable_uint<_Tp>::type;

  if ((__x %= __mod) < 0) __x += __mod;

  mul_type __y{1};

  while (__n) {
    if (__n & 1) (__y *= __x) %= __mod;
    __x = (mul_type)__x * __x % __mod;
    __n >>= 1;
  }

  return __y;
};

}  // namespace workspace
#line 10 "src/number_theory/sqrt_mod.hpp"

namespace workspace {

/**
 * @brief Compile time modular square root.
 *
 * @param __x
 * @param __mod Modulus
 * @return One if it exists. Otherwise -1.
 */
template <class _Tp>
constexpr std::enable_if_t<(is_integral_ext<_Tp>::value), _Tp> sqrt_mod(
    _Tp __x, _Tp __mod) noexcept {
  assert(__mod > 0);

  using mul_type = typename multiplicable_uint<_Tp>::type;

  if ((__x %= __mod) < 0) __x += __mod;

  if (!__x) return 0;

  if (__mod == 2) return __x;

  if (pow_mod(__x, __mod >> 1, __mod) != 1) return -1;

  _Tp __z = __builtin_ctz(__mod - 1), __q = __mod >> __z;

  mul_type __a = pow_mod(__x, (__q + 1) >> 1, __mod), __b = 2;
  while (pow_mod<_Tp>(__b, __mod >> 1, __mod) == 1) ++__b;
  __b = pow_mod<_Tp>(__b, __q, __mod);

  _Tp __shift = 0;

  for (auto __r = __a * __a % __mod * pow_mod(__x, __mod - 2, __mod) % __mod;
       __r != 1; (__r *= (__b *= __b) %= __mod) %= __mod) {
    auto __bsf = __z;

    for (auto __e = __r; __e != 1; --__bsf) (__e *= __e) %= __mod;

    while (++__shift != __bsf) (__b *= __b) %= __mod;

    (__a *= __b) %= __mod;
  }

  return __a;
};

}  // namespace workspace
#line 14 "src/algebra/modint.hpp"

namespace workspace {

namespace _modint_impl {

template <auto _Mod, unsigned _Storage> struct modint {
  static_assert(is_integral_ext<decltype(_Mod)>::value,
                "_Mod must be integral type.");

  using mod_type = std::make_signed_t<typename std::conditional<
      0 < _Mod, std::add_const_t<decltype(_Mod)>, decltype(_Mod)>::type>;

  using value_type = std::decay_t<mod_type>;

  using reference = value_type &;
  using const_reference = value_type const &;

  using mul_type = typename multiplicable_uint<value_type>::type;

  static mod_type mod;  // Modulus.

  static unsigned storage;

 private:
  template <class _Tp>
  using modint_if = std::enable_if_t<is_integral_ext<_Tp>::value, modint>;

  value_type value = 0;  // within [0, mod).

  struct direct_ctor_t {};
  constexpr static direct_ctor_t direct_ctor_tag{};

  // Direct constructor
  template <class _Tp>
  constexpr modint(_Tp __n, direct_ctor_t) noexcept : value(__n) {}

 public:
  constexpr modint() noexcept = default;

  template <class _Tp, class = std::enable_if_t<
                           std::is_convertible<_Tp, value_type>::value>>
  constexpr modint(_Tp __n) noexcept
      : value((__n %= mod) < _Tp(0) ? static_cast<value_type>(__n) + mod
                                    : static_cast<value_type>(__n)) {}

  constexpr modint(bool __n) noexcept : value(__n) {}

  constexpr operator reference() noexcept { return value; }

  constexpr operator const_reference() const noexcept { return value; }

  // unary operators {{
  constexpr modint operator++(int) noexcept {
    modint __t{*this};
    operator++();
    return __t;
  }

  constexpr modint operator--(int) noexcept {
    modint __t{*this};
    operator--();
    return __t;
  }

  constexpr modint &operator++() noexcept {
    if (++value == mod) value = 0;
    return *this;
  }

  constexpr modint &operator--() noexcept {
    if (!value)
      value = mod - 1;
    else
      --value;
    return *this;
  }

  constexpr modint operator+() const noexcept { return *this; }

  constexpr modint operator-() const noexcept {
    return {value ? mod - value : 0, direct_ctor_tag};
  }

  // }} unary operators

  // operator+= {{

  constexpr modint &operator+=(const modint &__x) noexcept {
    if ((value += __x.value) >= mod) value -= mod;
    return *this;
  }

  template <class _Tp> constexpr modint_if<_Tp> &operator+=(_Tp __x) noexcept {
    __x %= mod, value += __x;
    if (value < 0)
      value += mod;
    else if (value >= mod)
      value -= mod;
    return *this;
  }

  // }} operator+=

  // operator+ {{

  template <class _Tp>
  constexpr modint_if<_Tp> operator+(_Tp const &__x) const noexcept {
    return modint{*this} += __x;
  }

  constexpr modint operator+(modint __x) const noexcept { return __x += *this; }

  template <class _Tp>
  constexpr friend modint_if<_Tp> operator+(_Tp const &__x,
                                            modint __y) noexcept {
    return __y += __x;
  }

  // }} operator+

  // operator-= {{

  constexpr modint &operator-=(const modint &__x) noexcept {
    if ((value -= __x.value) < 0) value += mod;
    return *this;
  }

  template <class _Tp> constexpr modint_if<_Tp> &operator-=(_Tp __x) noexcept {
    __x %= mod, value -= __x;
    if (value < 0)
      value += mod;
    else if (value >= mod)
      value -= mod;
    return *this;
  }

  // }} operator-=

  // operator- {{

  template <class _Tp>
  constexpr modint_if<_Tp> operator-(_Tp const &__x) const noexcept {
    return modint{*this} -= __x;
  }

  constexpr modint operator-(const modint &__x) const noexcept {
    return modint{*this} -= __x;
  }

  template <class _Tp>
  constexpr friend modint_if<_Tp> operator-(_Tp __x,
                                            const modint &__y) noexcept {
    if (((__x -= __y.value) %= mod) < 0) __x += mod;
    return {__x, direct_ctor_tag};
  }

  // }} operator-

  // operator*= {{

  constexpr modint &operator*=(const modint &__x) noexcept {
    value =
        static_cast<value_type>(value * static_cast<mul_type>(__x.value) % mod);
    return *this;
  }

  template <class _Tp> constexpr modint_if<_Tp> &operator*=(_Tp __x) noexcept {
    value = static_cast<value_type>(
        value * ((__x %= mod) < 0 ? mul_type(__x + mod) : mul_type(__x)) % mod);
    return *this;
  }

  // }} operator*=

  // operator* {{

  constexpr modint operator*(const modint &__x) const noexcept {
    return {static_cast<mul_type>(value) * __x.value % mod, direct_ctor_tag};
  }

  template <class _Tp>
  constexpr modint_if<_Tp> operator*(_Tp __x) const noexcept {
    __x %= mod;
    if (__x < 0) __x += mod;
    return {static_cast<mul_type>(value) * __x % mod, direct_ctor_tag};
  }

  template <class _Tp>
  constexpr friend modint_if<_Tp> operator*(_Tp __x,
                                            const modint &__y) noexcept {
    __x %= mod;
    if (__x < 0) __x += mod;
    return {static_cast<mul_type>(__x) * __y.value % mod, direct_ctor_tag};
  }

  // }} operator*

 protected:
  static value_type _mem(value_type __x) {
    static std::vector<value_type> __m{0, 1};
    static value_type __i = (__m.reserve(storage), 1);
    while (__i < __x) {
      ++__i;
      __m.emplace_back(mod - mul_type(mod / __i) * __m[mod % __i] % mod);
    }
    return __m[__x];
  }

  static value_type _div(mul_type __r, value_type __x) noexcept {
    assert(__x != value_type(0));
    if (!__r) return 0;

    std::make_signed_t<value_type> __v{};
    bool __neg = __x < 0 ? __x = -__x, true : false;

    if (static_cast<decltype(storage)>(__x) < storage)
      __v = _mem(__x);
    else {
      value_type __y{mod}, __u{1}, __t;

      while (__x)
        __t = __y / __x, __y ^= __x ^= (__y -= __t * __x) ^= __x,
        __v ^= __u ^= (__v -= __t * __u) ^= __u;

      if (__y < 0) __neg ^= 1;
    }

    if (__neg)
      __v = 0 < __v ? mod - __v : -__v;
    else if (__v < 0)
      __v += mod;

    return __r == mul_type(1) ? static_cast<value_type>(__v)
                              : static_cast<value_type>(__r * __v % mod);
  }

 public:
  static void reserve(unsigned __n) noexcept {
    if (storage < __n) storage = __n;
  }

  // operator/= {{

  constexpr modint &operator/=(const modint &__x) noexcept {
    if (value) value = _div(value, __x.value);
    return *this;
  }

  template <class _Tp> constexpr modint_if<_Tp> &operator/=(_Tp __x) noexcept {
    if (value) value = _div(value, __x %= mod);
    return *this;
  }

  // }} operator/=

  // operator/ {{

  constexpr modint operator/(const modint &__x) const noexcept {
    if (!value) return {};
    return {_div(value, __x.value), direct_ctor_tag};
  }

  template <class _Tp>
  constexpr modint_if<_Tp> operator/(_Tp __x) const noexcept {
    if (!value) return {};
    return {_div(value, __x %= mod), direct_ctor_tag};
  }

  template <class _Tp>
  constexpr friend modint_if<_Tp> operator/(_Tp __x,
                                            const modint &__y) noexcept {
    if (!__x) return {};
    if ((__x %= mod) < 0) __x += mod;
    return {_div(__x, __y.value), direct_ctor_tag};
  }

  // }} operator/

  constexpr modint inv() const noexcept { return _div(1, value); }

  template <class _Tp> constexpr modint pow(_Tp __e) const noexcept {
    static_assert(not std::is_floating_point<_Tp>::value);

    modint __r{mod != 1, direct_ctor_tag};

    for (modint __b{__e < _Tp(0) ? __e = -__e, _div(1, value) : value,
                                   direct_ctor_tag};
         __e; __e /= 2, __b *= __b)
      if (__e % 2) __r *= __b;

    return __r;
  }

  template <class _Tp>
  constexpr friend modint pow(modint __b, _Tp __e) noexcept {
    static_assert(not std::is_floating_point<_Tp>::value);

    if (__e < _Tp(0)) {
      __e = -__e;
      __b.value = _div(1, __b.value);
    }

    modint __r{mod != 1, direct_ctor_tag};

    for (; __e; __e /= 2, __b *= __b)
      if (__e % 2) __r *= __b;

    return __r;
  }

  constexpr modint sqrt() const noexcept {
    return {sqrt_mod(value, mod), direct_ctor_tag};
  }

  friend constexpr modint sqrt(const modint &__x) noexcept {
    return {sqrt_mod(__x.value, mod), direct_ctor_tag};
  }

  friend std::istream &operator>>(std::istream &__is, modint &__x) noexcept {
    std::string __s;
    __is >> __s;
    bool __neg = false;
    if (__s.front() == '-') {
      __neg = true;
      __s.erase(__s.begin());
    }
    __x = 0;
    for (char __c : __s) __x = __x * 10 + (__c - '0');
    if (__neg) __x = -__x;
    return __is;
  }
};

template <auto _Mod, unsigned _Storage>
typename modint<_Mod, _Storage>::mod_type modint<_Mod, _Storage>::mod =
    _Mod > 0 ? _Mod : 0;

template <auto _Mod, unsigned _Storage>
unsigned modint<_Mod, _Storage>::storage = _Storage;

}  // namespace _modint_impl

constexpr unsigned _modint_default_storage = 1 << 24;

template <auto _Mod, unsigned _Storage = _modint_default_storage,
          typename = std::enable_if_t<(_Mod > 0)>>
using modint = _modint_impl::modint<_Mod, _Storage>;

template <unsigned _Id = 0, unsigned _Storage = _modint_default_storage>
using runtime_modint = _modint_impl::modint<-(signed)_Id, _Storage>;

template <unsigned _Id = 0, unsigned _Storage = _modint_default_storage>
using runtime_modint64 = _modint_impl::modint<-(int_least64_t)_Id, _Storage>;

}  // namespace workspace
#line 2 "src/utils/io/istream.hpp"

/**
 * @file istream.hpp
 * @brief Input Stream
 */

#include <cxxabi.h>

#line 12 "src/utils/io/istream.hpp"
#include <tuple>

#line 2 "lib/cxx17"

#line 2 "lib/cxx14"

#ifndef _CXX14_CONSTEXPR
#if __cplusplus >= 201402L
#define _CXX14_CONSTEXPR constexpr
#else
#define _CXX14_CONSTEXPR
#endif
#endif
#line 4 "lib/cxx17"

#ifndef _CXX17_CONSTEXPR
#if __cplusplus >= 201703L
#define _CXX17_CONSTEXPR constexpr
#else
#define _CXX17_CONSTEXPR
#endif
#endif

#ifndef _CXX17_STATIC_ASSERT
#if __cplusplus >= 201703L
#define _CXX17_STATIC_ASSERT static_assert
#else
#define _CXX17_STATIC_ASSERT assert
#endif
#endif

#line 22 "lib/cxx17"

#if __cplusplus < 201703L

namespace std {

/**
 *  @brief  Return the size of a container.
 *  @param  __cont  Container.
 */
template <typename _Container>
constexpr auto size(const _Container& __cont) noexcept(noexcept(__cont.size()))
    -> decltype(__cont.size()) {
  return __cont.size();
}

/**
 *  @brief  Return the size of an array.
 */
template <typename _Tp, size_t _Nm>
constexpr size_t size(const _Tp (&)[_Nm]) noexcept {
  return _Nm;
}

/**
 *  @brief  Return whether a container is empty.
 *  @param  __cont  Container.
 */
template <typename _Container>
[[nodiscard]] constexpr auto empty(const _Container& __cont) noexcept(
    noexcept(__cont.empty())) -> decltype(__cont.empty()) {
  return __cont.empty();
}

/**
 *  @brief  Return whether an array is empty (always false).
 */
template <typename _Tp, size_t _Nm>
[[nodiscard]] constexpr bool empty(const _Tp (&)[_Nm]) noexcept {
  return false;
}

/**
 *  @brief  Return whether an initializer_list is empty.
 *  @param  __il  Initializer list.
 */
template <typename _Tp>
[[nodiscard]] constexpr bool empty(initializer_list<_Tp> __il) noexcept {
  return __il.size() == 0;
}

struct monostate {};

}  // namespace std

#else

#include <variant>

#endif
#line 16 "src/utils/io/istream.hpp"

namespace workspace {

namespace _istream_impl {

template <class _Tp, typename = void> struct helper {
  helper(std::istream &__is, _Tp &__x) {
    if _CXX17_CONSTEXPR (has_begin<_Tp &>::value)
      for (auto &&__e : __x) helper<std::decay_t<decltype(__e)>>(__is, __e);
    else
      static_assert(has_begin<_Tp>::value, "istream unsupported type.");
  }
};

template <class _Tp>
struct helper<_Tp, std::__void_t<decltype(std::declval<std::istream &>() >>
                                          std::declval<_Tp &>())>> {
  helper(std::istream &__is, _Tp &__x) { __is >> __x; }
};

#ifdef __SIZEOF_INT128__

template <> struct helper<__uint128_t, void> {
  helper(std::istream &__is, __uint128_t &__x) {
    std::string __s;
    __is >> __s;
    bool __neg = false;
    if (__s.front() == '-') __neg = true, __s.erase(__s.begin());
    __x = 0;
    for (char __d : __s) {
      __x *= 10;
      __d -= '0';
      if (__neg)
        __x -= __d;
      else
        __x += __d;
    }
  }
};

template <> struct helper<__int128_t, void> {
  helper(std::istream &__is, __int128_t &__x) {
    std::string __s;
    __is >> __s;
    bool __neg = false;
    if (__s.front() == '-') __neg = true, __s.erase(__s.begin());
    __x = 0;
    for (char __d : __s) {
      __x *= 10;
      __d -= '0';
      if (__neg)
        __x -= __d;
      else
        __x += __d;
    }
  }
};

#endif  // INT128

template <class _T1, class _T2> struct helper<std::pair<_T1, _T2>> {
  helper(std::istream &__is, std::pair<_T1, _T2> &__x) {
    helper<_T1>(__is, __x.first), helper<_T2>(__is, __x.second);
  }
};

template <class... _Tp> struct helper<std::tuple<_Tp...>> {
  helper(std::istream &__is, std::tuple<_Tp...> &__x) { iterate(__is, __x); }

 private:
  template <class _Tuple, size_t _Nm = 0>
  void iterate(std::istream &__is, _Tuple &__x) {
    if _CXX17_CONSTEXPR (_Nm != std::tuple_size<_Tuple>::value) {
      helper<typename std::tuple_element<_Nm, _Tuple>::type>(
          __is, std::get<_Nm>(__x)),
          iterate<_Tuple, _Nm + 1>(__is, __x);
    }
  }
};

}  // namespace _istream_impl

/**
 * @brief A wrapper class for std::istream.
 */
class istream : public std::istream {
 public:
  /**
   * @brief Wrapped operator.
   */
  template <typename _Tp> istream &operator>>(_Tp &__x) {
    _istream_impl::helper<_Tp>(*this, __x);
    if (std::istream::fail()) {
      static auto once = atexit([] {
        std::cerr << "\n\033[43m\033[30mwarning: failed to read \'"
                  << abi::__cxa_demangle(typeid(_Tp).name(), 0, 0, 0)
                  << "\'.\033[0m\n\n";
      });
      assert(!once);
    }
    return *this;
  }
};

decltype(auto) cin = static_cast<istream &>(std::cin);

}  // namespace workspace
#line 2 "src/utils/io/ostream.hpp"

/**
 * @file ostream.hpp
 * @brief Output Stream
 */

#line 9 "src/utils/io/ostream.hpp"

#line 11 "src/utils/io/ostream.hpp"

namespace workspace {

template <class _Os> struct is_ostream {
  template <typename... _Args>
  static std::true_type __test(std::basic_ostream<_Args...> *);
  static std::false_type __test(void *);
  constexpr static bool value = decltype(__test(std::declval<_Os *>()))::value;
};

template <class _Os>
using ostream_ref =
    typename std::enable_if<is_ostream<_Os>::value, _Os &>::type;

/**
 * @brief Stream insertion operator for C-style array.
 *
 * @param __os Output stream
 * @param __a Array
 * @return Reference to __os.
 */
template <class _Os, class _Tp, size_t _Nm>
typename std::enable_if<bool(sizeof(_Tp) > 2), ostream_ref<_Os>>::type
operator<<(_Os &__os, const _Tp (&__a)[_Nm]) {
  if _CXX17_CONSTEXPR (_Nm) {
    __os << *__a;
    for (auto __i = __a + 1, __e = __a + _Nm; __i != __e; ++__i)
      __os << ' ' << *__i;
  }
  return __os;
}

/**
 * @brief Stream insertion operator for std::array.
 *
 * @param __os Output stream
 * @param __a Array
 * @return Reference to __os.
 */
template <class _Os, class _Tp, size_t _Nm>
ostream_ref<_Os> operator<<(_Os &__os, const std::array<_Tp, _Nm> &__a) {
  if _CXX17_CONSTEXPR (_Nm) {
    __os << __a[0];
    for (size_t __i = 1; __i != _Nm; ++__i) __os << ' ' << __a[__i];
  }
  return __os;
}

/**
 * @brief Stream insertion operator for std::pair.
 *
 * @param __os Output stream
 * @param __p Pair
 * @return Reference to __os.
 */
template <class _Os, class _T1, class _T2>
ostream_ref<_Os> operator<<(_Os &__os, const std::pair<_T1, _T2> &__p) {
  return __os << __p.first << ' ' << __p.second;
}

/**
 * @brief Stream insertion operator for std::tuple.
 *
 * @param __os Output stream
 * @param __t Tuple
 * @return Reference to __os.
 */
template <class _Os, class _Tp, size_t _Nm = 0>
typename std::enable_if<bool(std::tuple_size<_Tp>::value + 1),
                        ostream_ref<_Os>>::type
operator<<(_Os &__os, const _Tp &__t) {
  if _CXX17_CONSTEXPR (_Nm != std::tuple_size<_Tp>::value) {
    if _CXX17_CONSTEXPR (_Nm) __os << ' ';
    __os << std::get<_Nm>(__t);
    operator<<<_Os, _Tp, _Nm + 1>(__os, __t);
  }
  return __os;
}

template <class _Os, class _Container,
          typename = decltype(std::begin(std::declval<_Container>()))>
typename std::enable_if<
    !std::is_convertible<std::decay_t<_Container>, std::string>::value &&
        !std::is_convertible<std::decay_t<_Container>, char *>::value,
    ostream_ref<_Os>>::type
operator<<(_Os &__os, const _Container &__cont) {
  bool __h = true;
  for (auto &&__e : __cont) __h ? __h = 0 : (__os << ' ', 0), __os << __e;
  return __os;
}

#ifdef __SIZEOF_INT128__

/**
 * @brief Stream insertion operator for __int128_t.
 *
 * @param __os Output Stream
 * @param __x 128-bit integer
 * @return Reference to __os.
 */
template <class _Os> ostream_ref<_Os> operator<<(_Os &__os, __int128_t __x) {
  if (!__x) return __os << '0';
  if (__x < 0) __os << '-';
  char __s[40], *__p = __s;
  while (__x) {
    auto __d = __x % 10;
    *__p++ = '0' + (__x < 0 ? -__d : __d);
    __x /= 10;
  }
  *__p = 0;
  for (char *__t = __s; __t < --__p; ++__t) *__t ^= *__p ^= *__t ^= *__p;
  return __os << __s;
}

/**
 * @brief Stream insertion operator for __uint128_t.
 *
 * @param __os Output Stream
 * @param __x 128-bit unsigned integer
 * @return Reference to __os.
 */
template <class _Os> ostream_ref<_Os> operator<<(_Os &__os, __uint128_t __x) {
  if (!__x) return __os << '0';
  char __s[40], *__p = __s;
  while (__x) *__p++ = '0' + __x % 10, __x /= 10;
  *__p = 0;
  for (char *__t = __s; __t < --__p; ++__t) *__t ^= *__p ^= *__t ^= *__p;
  return __os << __s;
}

#endif

}  // namespace workspace
#line 7 "test/library-checker/system_of_linear_equations.test.cpp"

namespace workspace {

using mint = modint<998244353>;
using mat = matrix<mint>;

void main() {
  // start here!

  size_t n, m;
  cin >> n >> m;

  lu_decomposition lu = [&] {
    mat a(n, m);
    cin >> a;
    return a;
  }();

  auto res = lu.solve([&] {
    std::vector<mint> b(n);
    cin >> b;
    return b;
  }());

  if (!res.first) {
    std::cout << "-1\n";
    return;
  }

  auto ker = lu.kernel();
  std::cout << ker.size() << "\n" << res.second << "\n";
  for (auto &&v : ker) std::cout << v << "\n";
}

}  // namespace workspace

int main() { workspace::main(); }
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