#include <iostream>

using namespace std;
using ll = long long;
const int MX = 1000010;
ll f[MX],inv[MX],fi[MX];
constexpr ll mod = 998244353;
void solve(){
    inv[1] = 1;
    for(int i=2;i<MX;i++){
        inv[i] = mod - (mod/i)*inv[mod%i]%mod;
    }
   f[0] = fi[0] = 1;
    for(int i=1;i<MX;i++){
        f[i] = f[i-1]*i%mod;
        fi[i] = fi[i-1]*inv[i]%mod;
    }
}

ll nck(ll n, ll k){
    if(n<0 || k<0 || n<k) return 0;
    return f[n]*fi[k]%mod*fi[n-k]%mod;
}

int main(){
    ll i,n,m,a,b,ans = 0; cin >> n >> m >> a >> b;
    solve();
    for(i=0;i<=m - 1 - (n - 1)*a;i++){
        (ans += nck(min(b,m - 1 - i) - (n - 1)*a + n - 1,n - 1)) %= mod;
    }
    cout << ans*f[n]%mod << endl;
}