取模类
集成了常见的取模四则运算，运算速度与手动取模相差无几，效率极高。
using i64 = long long;template<class T> constexpr T mypow(T n, i64 k) {T r = 1;for (; k; k /= 2, n *= n) {if (k % 2) {r *= n;}}return r;
}template<class T> constexpr T power(int n) {return mypow(T(2), n);
}template<const int &MOD> struct Zmod {int x;Zmod(signed x = 0) : x(norm(x % MOD)) {}Zmod(i64 x) : x(norm(x % MOD)) {}constexpr int norm(int x) const noexcept {if (x < 0) [[unlikely]] {x += MOD;}if (x >= MOD) [[unlikely]] {x -= MOD;}return x;}explicit operator int() const {return x;}constexpr int val() const {return x;}constexpr Zmod operator-() const {Zmod val = norm(MOD - x);return val;}constexpr Zmod inv() const {assert(x != 0);return mypow(*this, MOD - 2);}friend constexpr auto &operator>>(istream &in, Zmod &j) {int v;in >> v;j = Zmod(v);return in;}friend constexpr auto &operator<<(ostream &o, const Zmod &j) {return o << j.val();}constexpr Zmod &operator++() {x = norm(x + 1);return *this;}constexpr Zmod &operator--() {x = norm(x - 1);return *this;}constexpr Zmod operator++(signed) {Zmod res = *this;++*this;return res;}constexpr Zmod operator--(signed) {Zmod res = *this;--*this;return res;}constexpr Zmod &operator+=(const Zmod &i) {x = norm(x + i.x);return *this;}constexpr Zmod &operator-=(const Zmod &i) {x = norm(x - i.x);return *this;}constexpr Zmod &operator*=(const Zmod &i) {x = i64(x) * i.x % MOD;return *this;}constexpr Zmod &operator/=(const Zmod &i) {return *this *= i.inv();}constexpr Zmod &operator%=(const int &i) {return x %= i, *this;}friend constexpr Zmod operator+(const Zmod i, const Zmod j) {return Zmod(i) += j;}friend constexpr Zmod operator-(const Zmod i, const Zmod j) {return Zmod(i) -= j;}friend constexpr Zmod operator*(const Zmod i, const Zmod j) {return Zmod(i) *= j;}friend constexpr Zmod operator/(const Zmod i, const Zmod j) {return Zmod(i) /= j;}friend constexpr Zmod operator%(const Zmod i, const int j) {return Zmod(i) %= j;}friend constexpr bool operator==(const Zmod i, const Zmod j) {return i.val() == j.val();}friend constexpr bool operator!=(const Zmod i, const Zmod j) {return i.val() != j.val();}friend constexpr bool operator<(const Zmod i, const Zmod j) {return i.val() < j.val();}friend constexpr bool operator>(const Zmod i, const Zmod j) {return i.val() > j.val();}
};int MOD[] = {998244353, 1000000007};
using Z = Zmod<MOD[1]>;