#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef long double ld;
typedef complex<double> comp;
const ll inf=1e9+7;
const ll mod=998244353;
const int MAX=300010;

//Combination
long long extGCD(long long a,long long mod,long long &x,long long &y){
    if(mod==0){
        x=1;
        y=0;
        return a;
    }
    long long d=extGCD(mod,a%mod,y,x);
    y-=(a/mod)*x;
    return d;
}
long long invmod(long long a,long long mod){
    long long x,y;
    extGCD(a,mod,x,y);
    x%=mod;
    if(x<0)x+=mod;
    return x;
}
ll fac[MAX],finv[MAX],inv[MAX];
void combinit(){
    fac[0]=fac[1]=1;
    finv[0]=finv[1]=1;
    inv[1]=1;
    REP(i,2,MAX){
        fac[i]=fac[i-1]*i%mod;
        inv[i]=invmod(i,mod);
        finv[i]=finv[i-1]*inv[i]%mod;
    }
}
ll comb(ll n,ll k){
    if(n<k)return 0;
    if(n<0||k<0)return 0;
    return fac[n]*(finv[k]*finv[n-k]%mod)%mod;
}

signed main(){
    ll n,m,a,b;cin>>n>>m>>a>>b;
    if((n-1)*a>b){
        cout<<0<<endl;
        return 0;
    }
    combinit();
    ll y=b-(n-1)*a+1;
    ll ans=0;
    rep(i,y){
        ans=(ans+comb(b-(n-1)*a+n-2-i,n-2)%mod*(m-b+i)%mod)%mod;
    }
    ll k=1;
    REP(i,1,n+1){
        k=k*i%mod;
    }
    ans=ans*k%mod;
    if(ans<0)ans+=mod;
    cout<<ans<<endl;
}