#pragma GCC optimize ("O2")
#pragma GCC target ("avx2")
#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

const int mod = 998244353;
const int IMAX = 400000;
constexpr ll modpow(ll A, ll B) {
	ll kotae = 1;
	while (B > 0) {
		if (B & 1) kotae = kotae * A % mod;
		A = A * A % mod;
		B >>= 1;
	}
	return kotae;
}
class unko {
public:
	int fac[IMAX + 1], ifac[IMAX + 1], inv[IMAX + 1];
	unko() : fac(), ifac(), inv() {
		fac[0] = 1;
		rep1(i, IMAX) fac[i] = ll(fac[i - 1]) * i % mod;
		ifac[IMAX] = modpow(fac[IMAX], mod - 2);
		for (int i = IMAX; i > 0; i--) ifac[i - 1] = ll(ifac[i]) * i % mod;
		inv[0] = 1;
		rep1(i, IMAX) inv[i] = ll(ifac[i]) * fac[i - 1] % mod;
	}
	int comb(int A, int B) {
		return ll(fac[A]) * ifac[B] % mod * ifac[A - B] % mod;
	}
} f;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	ll N, M, A, B;
	cin >> N >> M >> A >> B;

	ll kotae = 0;

	for (int D = 1; D <= B; D++) {
		ll are = D - A * (N - 1);
		if (are >= 0) {
			ll tmp = f.comb(are + N - 2, N - 2);
			tmp = tmp * (M - D) % mod;
			kotae += tmp;
		}
	}
	kotae %= mod;
	rep1(i, N) {
		kotae = kotae * i % mod;
	}
	co(kotae);


	Would you please return 0;
}