#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;

typedef long long ll;
typedef pair<int, int> Pii;

const ll MOD = 1000000007;
const int FACT_MAX = 1300001;

ll fact[FACT_MAX], rfact[FACT_MAX];

ll perm(ll n, ll r){
    return (fact[n] * rfact[r]) % MOD;
}

ll comb(ll n, ll r){
    return (perm(n, r) * rfact[n-r]) % MOD;
}

void init(ll n){
    fact[0] = fact[1] = 1;
    rfact[0] = rfact[1] = 1;
    for(int i=2;i<=n;++i) {
        fact[i] = (fact[i-1] * (ll)i) % MOD;
        rfact[i] = 1;
        ll k = MOD-2;
        ll a = fact[i];
        while(k > 0){
            if(k & 1){
                rfact[i] *= a;
                rfact[i] %= MOD;
            }
            a *= a;
            a %= MOD;
            k  >>= 1;
        }
    }
}

int main() {
    ll N,M,D1,D2;
    cin >> N >> M >> D1 >> D2;

    init(FACT_MAX);

    ll Mrest = M - 1 - D1*(N-1);
    ll ans = 0LL;
    for(int i=0;i<N&&Mrest>=0;++i) {
        ans += MOD + (i%2?-1:1) * (comb(N-1, i) * comb(N+Mrest, Mrest)) % MOD;
        ans %= MOD;
        Mrest -= (D2-D1+1);
    }
    cout << ans << endl;
}