#include<bits/stdc++.h>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
typedef long long ll;
const ll mod=1e9+7 ;


vector<ll> inv,fact,invfact;
void mod_build(int n=101010){
	fact.resize(n+1);
	inv.resize(n+1);
	invfact.resize(n+1);
	fact[0]=inv[0]=invfact[0]=1;
	inv[1]=1;
	rep(i,n){
		fact[i+1]=fact[i]*(i+1)%mod;
		if(i>0)inv[i+1]=mod-inv[mod%(i+1)]*(mod/(i+1))%mod;
		invfact[i+1]=invfact[i]*inv[i+1]%mod;
	}
}
ll perm(int n,int k){
	if(n<0||k<0||k>n)return 0;
	return fact[n]*invfact[n-k]%mod;
}
ll comb(ll n,ll k){
	if(n<0||k<0||k>n)return 0;
	return (fact[n]*invfact[n-k]%mod)*invfact[k]%mod;
}

int main(){
	ll n,m,d1,d2;
	cin>>n>>m>>d1>>d2;
	assert(2<=n&&n<=300000);
	assert(1<=m&&m<=1000000);
	assert(0<=d1&&d1<=d2&&d2<=m);
	m-=(n-1)*(d1-1);
	d2-=d1-1;
	mod_build(max(m+1,n));
	ll ans=0;
	rep(i,n){
		ll ret=comb(m-d2*i,n)*comb(n-1,i)%mod;
		if(i%2)ans+=mod-ret;
		else ans+=ret;
	}
	cout<<ans%mod<<endl;
	return 0;
}