#include <iostream>
#include <cstdio>

using namespace std;

typedef long long LL;

const int N = 1300010, MOD = 1000000007;

int n, m, d1, d2, fac[N], inv[N], ifac[N];

int C(int x, int y) {
    if (x < y || y < 0) return 0;
    return 1LL * fac[x] * ifac[y] % MOD * ifac[x - y] % MOD;
}

void Init() {
    fac[0] = ifac[0] = 1;
    fac[1] = ifac[1] = inv[1] = 1;
    for (int i = 2; i < N; ++i) {
        fac[i] = 1LL * fac[i - 1] * i % MOD;
        inv[i] = 1LL * (MOD - MOD / i) * inv[MOD % i] % MOD;
        ifac[i] = 1LL * ifac[i - 1] * inv[i] % MOD;
    }
}

int main() {
    Init();

    scanf("%d%d%d%d", &n, &m, &d1, &d2);
    int d = d2 - d1;
    LL y = m - 1LL * (n - 1) * d1 - 1LL;
    LL ans = 0LL;
    for (int i = 0; i < n; ++i) {
        LL w = y - 1LL * i * (d + 1);
        if (w < 0) break;
        int v = 1LL * C(n - 1, i) * C(w + n, n) % MOD;
        if (i & 1) ans -= v;
        else ans += v;
    }
    printf("%lld\n", (ans % MOD + MOD) % MOD);

    return 0;
}