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

const int64_t MOD = 1e9+7;
void add(int64_t& a, int64_t b){
    a = (a+b) % MOD;
}

vector<int64_t> fact, seq_inv, fact_inv;

void create_fact_mod(int num){
    fact[0] = 1;
    fact[1] = 1;
    for(int i=2; i<=num; i++){
        fact[i] = fact[i-1] * i % MOD;
    }
}

void create_seq_inv_mod(int num){
    seq_inv[0] = 1;
    seq_inv[1] = 1;
    for(int i=2; i<=num; i++){
        seq_inv[i] = (MOD - MOD/i) * seq_inv[MOD%i] % MOD;
    }
}

void create_fact_inv_mod(int num){
    fact_inv[0] = 1;
    fact_inv[1] = 1;
    for(int i=2; i<=num; i++){
        fact_inv[i] = fact_inv[i-1] * seq_inv[i] % MOD;
    }
}

void create_mod_tables(int num){
    fact.resize(num+1);
    seq_inv.resize(num+1);
    fact_inv.resize(num+1);
    create_fact_mod(num);
    create_seq_inv_mod(num);
    create_fact_inv_mod(num);
}

int64_t comb_mod(int n, int k){
    return fact[n] * fact_inv[n-k] % MOD * fact_inv[k] % MOD;
}

int64_t perm_mod(int n, int k){
    return fact[n] * fact_inv[n-k] % MOD;
}


int main(){
    int64_t N, M, D1, D2;
    cin >> N >> M >> D1 >> D2;

    int64_t diff = M-1 - (N-1) * D1;
    if(diff < 0){
        cout << 0 << endl;
        return 0;
    }
    int64_t D = D2 - D1;

    create_mod_tables(1400000);

    int64_t ans = 0;
    for(int i=0; i<N; i++){
        int64_t diff2 = diff - i*(D+1);
        if(diff2 < 0) continue;
        int64_t result = comb_mod(N+diff2, diff2) * comb_mod(N-1, i) % MOD;
        add(ans, i%2 ? MOD - result : result);
    }
    cout << ans << endl;
    return 0;
}