#include <iostream>
using namespace std;

#define REP(i, s) for (int i = 0; i < s; ++i)
#define ALL(v) (v.begin(), v.end())
#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
#define EACH(i, s) for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)

const int MAX = 11000000;
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];
void COMinit(){
    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;
    }
}
long long COM(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;
}



long long N, M, D1, D2;
long long solve() {
    long long D = D2 - D1;
    long long x = M - 1 - D1 * (N-1);
    if (x < 0) return 0;

    long long res = 0;
    for (long long p = 0; p <= N-1; ++p) {
        long long tmp = COM(N-1, p) * COM(x - p*(D+1) + N, N) % MOD;
        if (p % 2 == 0) res += tmp;
        else res += MOD - tmp;
        res %= MOD;
    }
    return res;
}

int main() {
    COMinit();
    cin >> N >> M >> D1 >> D2;
    cout << solve() << endl;
}