#pragma GCC optimize("Ofast") #include #include #include using namespace std; using namespace __gnu_pbds; using ll = long long; using ull = unsigned long long; using pii = pair; using pll = pair; #define rep(i, n) for(int i = 0; i < (n); ++i) #define all(x) (x).begin(),(x).end() constexpr char ln = '\n'; //constexpr long long MOD = 1000000007; constexpr long long MOD = 998244353; template inline bool chmax(T1 &a, T2 b) { if (a < b) { a = b; return true;} return false; } template inline bool chmin(T1 &a, T2 b) { if (a > b) { a = b; return true;} return false; } inline int popcount(int x) {return __builtin_popcount(x);} inline int popcount(long long x) {return __builtin_popcountll(x);} void print() { cout << "\n"; } template void print(const T &x, const Args &... args) { cout << x << " "; print(args...); } /////////////////////////////////////////////////////////////////////////////////////////////////////////////// template struct ModInt { using u64 = uint_fast64_t; u64 a; constexpr ModInt(const long long x = 0) noexcept : a(x >= 0 ? x % Modulus : (Modulus - (-x) % Modulus) % Modulus) {} constexpr u64 &value() noexcept {return a;} constexpr const u64 &value() const noexcept {return a;} constexpr ModInt operator+(const ModInt rhs) const noexcept {return ModInt(*this) += rhs;} constexpr ModInt operator-(const ModInt rhs) const noexcept {return ModInt(*this) -= rhs;} constexpr ModInt operator*(const ModInt rhs) const noexcept {return ModInt(*this) *= rhs;} constexpr ModInt operator/(const ModInt rhs) const noexcept {return ModInt(*this) /= rhs;} constexpr ModInt operator^(const long long rhs) const noexcept {return ModInt(*this) ^= rhs;} constexpr bool operator==(const ModInt &rhs) const noexcept {return a == rhs.a;} constexpr bool operator!=(const ModInt &rhs) const noexcept {return a != rhs.a;} constexpr ModInt &operator+=(const ModInt rhs) noexcept { a += rhs.a; if (a >= Modulus) { a -= Modulus; } return *this; } constexpr ModInt &operator-=(const ModInt rhs) noexcept { if (a < rhs.a) { a += Modulus; } a -= rhs.a; return *this; } constexpr ModInt &operator*=(const ModInt rhs) noexcept { a = a * rhs.a % Modulus; return *this; } constexpr ModInt &operator/=(ModInt rhs) noexcept { u64 exp = Modulus - 2; while (exp) { if (exp&1) *this *= rhs; exp >>= 1; rhs *= rhs; } return *this; } constexpr ModInt &operator^=(long long exp) noexcept { ModInt rhs = a; a = 1; while (exp) { if (exp&1) *this *= rhs; exp >>= 1; rhs *= rhs; } return *this; } friend ostream &operator<<(ostream& os, const ModInt& rhs) noexcept {return os << rhs.a;} friend istream &operator>>(istream& is, ModInt& rhs) noexcept {long long a; is >> a; rhs = a; return is;} }; using mint = ModInt; struct ModCombination { vector Fac; vector Facinv; ModCombination(int x) { Fac.resize(x+1); Facinv.resize(x+1); Fac[0] = 1; for (int i = 0; i < x; ++i) Fac[i+1] = Fac[i]*(i+1); Facinv[x] = Fac[0]/Fac[x]; for (int i = x; i > 0; --i) Facinv[i-1] = Facinv[i]*i; } mint get(int n, int k) { if (k < 0 || k > n) return 0; return Fac[n]*Facinv[k]*Facinv[n-k]; } }; int main() { ios::sync_with_stdio(false); cin.tie(nullptr); ll N,M,A,B; cin >> N >> M >> A >> B; ModCombination MC(500000); mint ans = 0; for (ll i = 1; i <= M; i++) { if (i+A*(N-1) > M) continue; ll val = min(M,i+B) - i - A*(N-1); ans += MC.get(N-1+val,val); } ans *= MC.Fac[N]; cout << ans << ln; }