#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

#include <bits/stdc++.h>
using namespace std;

const ll MAX = 310000;
const ll MOD = 998244353;

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

void init(){
  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;
  }
}

ll nCr(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;
}

ll nPr(int n,int k){
  if(n<k) return 0;
  if(n<0 || k<0) return 0;
  return fac[n]*finv[n-k]%MOD;
}

int main(){
  ll n,m,a,b;
  cin>>n>>m>>a>>b;
  
  init();
  
  ll ans=0;
  for(int i=1;i<=m;i++) ans=(ans+nCr(min(b,m-i)-(n-1)*(a-1),n-1))%MOD;
  cout<<(ans*nPr(n,n))%MOD<<endl;

  return 0;
}