#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

ll mod_pow(ll x, ll n, ll mod) {
    ll res = 1;
    while (n > 0) {
        if (n & 1) res = res * x % mod;
        x = x * x % mod;
        n >>= 1;
    }
    return res;
}

int main() {
    ll N, M, A, B, MOD = 998244353;
    vector<ll> f(300001, 1);
    rep(i, 300000) {
        f[i + 1] = (f[i] * (i + 1)) % MOD;
    }
    cin >> N >> M >> A >> B;
    ll ans = 0;
    for (int i = 1; i <= M; i++) {
        ll x = min(i + B, M) - A * (N - 1) - i;
        if (x < 0) break;
        ll a = (f[x + N - 1] * mod_pow(f[N - 1], MOD - 2, MOD)) % MOD;
        a = (a * mod_pow(f[x], MOD - 2, MOD)) % MOD;
        ans = (ans + a) % MOD;
    }
    for (int i = 1; i <= N; i++) ans = (ans * i) % MOD;
    cout << ans << "\n";
}