#include<iostream>
using namespace std;
const long mod=998244353;
int N,M,A,B;
long fac[4<<17],inv[4<<17];
long power(long a,long b){return b?power(a*a%mod,b/2)*(b%2?a:1)%mod:1;}
long comb(int a,int b){return fac[a]*inv[b]%mod*inv[a-b]%mod;}
main()
{
	cin>>N>>M>>A>>B;
	fac[0]=1;
	for(int i=1;i<4<<17;i++)fac[i]=fac[i-1]*i%mod;
	inv[(4<<17)-1]=power(fac[(4<<17)-1],mod-2);
	for(int i=(4<<17)-1;i--;)inv[i]=inv[i+1]*(i+1)%mod;
	if((long)(N-1)*A>B)
	{
		cout<<0<<endl;
		return 0;
	}
	int T=B-(N-1)*A;
	long ans=0;
	for(int i=0;i<=T;i++)
	{
		(ans+=comb(N-1+i,N-1)*(M-i-(N-1)*A))%=mod;
	}
	for(int i=1;i<=N;i++)ans=ans*i%mod;
	cout<<ans<<endl;
}