#define DEBUG 1 #include #define loop(n) for (lint ngtkana_is_a_genius = 0; ngtkana_is_a_genius < lint(n); ngtkana_is_a_genius++) #define rep(i, begin, end) for (lint i = lint(begin); (i) < lint(end); i++) #define all(v) v.begin(), v.end() #define rand(l, r) std::uniform_int_distribution<>(l, r)(mt) using lint = long long; auto mt = std::mt19937_64(std::random_device{}()); auto cmn = [](auto&& pow2, auto b){ if (pow2 > b) {pow2 = b; return true;} return false; }; auto cmx = [](auto&& pow2, auto b){ if (pow2 < b) {pow2 = b; return true;} return false; }; void debug_impl() { std::cerr << std::endl; } template void debug_impl(Head head, Tail... tail) { std::cerr << " " << head; debug_impl(tail...); } #if DEBUG #define debug(...)\ do {\ std::cerr << std::boolalpha << "[" << #__VA_ARGS__ << "]:";\ debug_impl(__VA_ARGS__);\ std::cerr << std::noboolalpha;\ } while (false) #else #define debug(...) {} #endif template T inverse(T pow2, T m) { T u = 0, v = 1; while (pow2 != 0) { T t = m / pow2; m -= t * pow2; std::swap(pow2, m); u -= t * v; std::swap(u, v); } assert(m == 1); return u; } template class modular { private: int value; public: constexpr modular() = default; constexpr modular(const modular&) = default; constexpr modular(modular&&) = default; modular& operator=(const modular&) = default; modular& operator=(modular&&) = default; template modular (const U& x) {value = normalize(x);} template static auto normalize(const U& x) { int v = static_cast(-mod() <= x && x < mod() ? x : x % mod()); if (v < 0) v += mod(); return v; } auto const& operator()() const { return value; } template explicit operator U() const { return static_cast(value); } constexpr static auto mod() { return T::value; } auto& operator+=(const modular& other) { if ((value += other.value) >= mod()) value -= mod(); return *this; } auto& operator-=(const modular& other) { if ((value -= other.value) < 0) value += mod(); return *this; } template auto& operator+=(const U& other) {return *this += modular(other); } template auto& operator-=(const U& other) {return *this -= modular(other); } auto operator-() const { return modular(-value); } auto& operator++() {return *this += 1;} auto& operator--() {return *this -= 1;} auto operator++(int) {modular result(*this); operator++(); return result;} auto operator--(int) {modular result(*this); operator--(); return result;} template auto& operator*=(const modular& rhs) { value = normalize(static_cast(value) * static_cast(rhs.value)); return *this; } auto& operator/=(const modular& other) { return *this *= modular(inverse(other.value, mod())); } }; template struct is_modular : std::false_type {}; template struct is_modular > : std::true_type{}; template constexpr bool is_modular_v = is_modular::value; template bool operator==(const modular& lhs, const modular& rhs) { return lhs() == rhs(); } template bool operator==(const modular& lhs, U rhs) { return lhs == modular(rhs); } template bool operator==(U lhs, const modular& rhs) { return modular(lhs) == rhs; } template bool operator!=(const modular& lhs, const modular& rhs) { return !(lhs == rhs); } template bool operator!=(const modular& lhs, U rhs) { return !(lhs == rhs); } template bool operator!=(U lhs, const modular& rhs) { return !(lhs == rhs); } template modular operator+(const modular& lhs, const modular& rhs) { return modular(lhs) += rhs; } template modular operator+(const modular& lhs, U rhs) { return modular(lhs) += rhs; } template modular operator+(U lhs, const modular& rhs) { return modular(lhs) += rhs; } template modular operator-(const modular& lhs, const modular& rhs) { return modular(lhs) -= rhs; } template modular operator-(const modular& lhs, U rhs) { return modular(lhs) -= rhs; } template modular operator-(U lhs, const modular& rhs) { return modular(lhs) -= rhs; } template modular operator*(const modular& lhs, const modular& rhs) { return modular(lhs) *= rhs; } template modular operator*(const modular& lhs, U rhs) { return modular(lhs) *= rhs; } template modular operator*(U lhs, const modular& rhs) { return modular(lhs) *= rhs; } template modular operator/(const modular& lhs, const modular& rhs) { return modular(lhs) /= rhs; } template modular operator/(const modular& lhs, U rhs) { return modular(lhs) /= rhs; } template modular operator/(U lhs, const modular& rhs) { return modular(lhs) /= rhs; } template modular power (const modular& pow2, U b) { assert(b >= 0); modular x = pow2, ret = 1; for (; b > 0; b /= 2) { if (b % 2 == 1) ret *= x; x *= x; } return ret; } template std::string to_string(const modular& pow2) { return std::to_string(pow2()); } template auto operator<<(std::ostream& os, const T& pow2) -> std::enable_if_t, std::ostream&>{ return os << pow2(); } template auto operator>>(std::istream& is, T& pow2) -> std::enable_if_t, std::istream&> { long long x; is >> x; pow2 = T(x); return is; } // using mod_type = int; // struct variable_mod { static mod_type value; }; // mod_type variable_mod::value; // mod_type& mod = variable_mod::value; // using mint = modular< variable_mod >; constexpr int mod = 998244353; using mint = modular, mod>>; int main() { std::cin.tie(0); std::cin.sync_with_stdio(false); lint n, m; std::cin >> n >> m; std::vectorpow2(n+m+1); pow2.at(0)=1; for(std::size_t i=1;i