#include <stdio.h>

const int mod = 1000000007;
int n, m, d1, d2;

/*
[x^m] 1/(1-x) x/(1-x) (x^d1 + ... + x^d2)^{n-1}
[x^m] x/(1-x)^2 x^{d1 (n-1)} [(1 - x^{d2-d1+1}) / (1-x) ]^{n-1}
[x^{m-d1(n-1)-1}] (1 - x^{d2-d1+1})^{n-1} / (1-x)^{n+1}

[x^{k}] (1 - x^{e})^{n-1} / (1-x)^{n+1}

\sum_i (-1)^i\binom{n-1}{i} \binom{k-ie+n}{n}
=
\sum_i (-1)^i (k-ie+n)! / (n i! (n-1-i)! (k-ie)!) 
*/

int modpow(int x, int n){
  int r=1;
  for(;n;n>>=1){
    if(n&1) r = (long long) r * x % mod;
    x = (long long) x * x % mod;
  }
  return r;
}

int fact[1500000];
int ifact[1500000];

int main(){
  int i, k, e, r;
  scanf("%d%d%d%d",&n,&m,&d1,&d2);
  fact[0] = 1;
  for(i=1;i<n+m;i++)
    fact[i] = (long long) fact[i-1] * i % mod;
  i--;
  ifact[i]=modpow(fact[i], mod-2);
  for(i--;i>=0;i--)
    ifact[i] = (long long) ifact[i+1] * (i+1) % mod;
  if(m - 1 < (long long) d1*(n-1)){
    puts("0");
    return 0;
  }

  k = m - d1*(n-1) - 1;
  e = d2 - d1 + 1;

  r = 0;
  for(i=0; i<=n-1 && i*e <= k; i++){
    int z;
    z = (long long) fact[k-i*e+n] * ifact[i] % mod * ifact[n-1-i] % mod * ifact[k-i*e] % mod;
    if(i&1) r += mod-z;
    else r += z;
    if(r >= mod) r -= mod;
  }
  r = (long long) r * modpow(n, mod-2) % mod;
  printf("%d\n", r);

  return 0;
}