#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=1444999999994;
ll mod=998244353;
const int MAX = 610000;
const int MOD = mod;

long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

// 二項係数計算
long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
int main(){
    ll n,m,a,b;
    cin >> n >> m >> a >> b;
    vector<ll>x(m,0);
    COMinit();
    for (ll i = n-1; i >=0; i--)
    {
        if (i*a+(n-1-i)*(b+1)>=m)
        {
            break;
        }
        ll y=i*a+(n-1-i)*(b+1);
        x[y]=COM(n-1,i);
        if ((n-1-i)%2)
        {
            x[y]*=-1;
            x[y]+=mod;
            x[y]%=mod;
        }
    }
    vector<ll>y(m+1,0);
    for (ll i = 0; i <=m; i++)
    {
        y[i]=COM(n-2+i,n-2);
    }
    vector<ll>z=convolution<998244353>(x,y);
    ll ans=0;
    vector<ll>kaijo(n+100,1);
    for (ll i = 1; i < kaijo.size(); i++)
    {
        kaijo[i]=kaijo[i-1]*i;
        kaijo[i]%=mod;
    }
    for (ll i = 0; i <m; i++)
    {
        if (i>b)
        {
            continue;
        }
        
        ans+=(((z[i]*(m-i))%mod)*kaijo[n])%mod;
        ans%=mod;
    }
    cout << ans << endl;
}