#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>

using namespace std;

const long long modc=998244353, MAX=1000000;
vector<long long> f, finv;

long long inv(long long x){
    long long ans = 1, e = modc-2;
    x %= modc;

    while (e > 0){
        if ((e & 1LL)) ans = (ans * x) % modc;
        e = e >> 1LL;
        x = (x*x) % modc;
    }

    return ans;
}


void init(){
    f.resize(MAX+1); finv.resize(MAX+1);
    f[0] = 1;
    for (int i=1; i<=MAX; i++) f[i] = (f[i-1]*i) % modc;
    finv[MAX] = inv(f[MAX]);
    for (int i=MAX-1; i>=0; i--) finv[i] = (finv[i+1] * (i+1)) % modc;
}

long long C(long long n, long long k){ 
    if (n < k || k < 0) return 0;

    return (((f[n] * finv[k]) % modc) * finv[n-k]) % modc;
}

long long P(long long n, long long k){
    if (n < k || k < 0) return 0;

    return (f[n] * finv[n-k]) % modc;
}

int main(){

    init();
    long long N, M, A, B, ans=0, mx;
    cin >> N >> M >> A >> B;

    mx = B-(N-1)*A;

    for (int i=0; i<=mx; i++){
        ans += (C(N-2+i, N-2) * max(M-(N-1)*A-i, 0LL)) % modc;
        ans %= modc;
    }

    ans *= P(N, N);
    ans %= modc;

    cout << ans << endl;

    return 0;
}