#include <bits/stdc++.h>
#define mp make_pair
#define all(vec) vec.begin(), vec.end()
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = 1LL << 30;
const ll LINF = 1LL << 60;
const double eps = 1e-9;
const ll MOD = 1000000007LL;
template <typename T>
void chmin(T &a, T b) {
    a = min(a, b);
};
template <typename T>
void chmax(T &a, T b) {
    a = max(a, b);
};
template <typename T>
vector<T> make_v(size_t a) {
    return vector<T>(a);
}
template <typename T, typename... Ts>
auto make_v(size_t a, Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) {
    t = v;
}
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) {
    for(auto &e : t) fill_v(e, v);
};
int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};
ll mpow(ll x, ll n) {
    ll res = 1;
    while(n > 0) {
        if(n & 1) {
            res = res * x % MOD;
        }
        n >>= 1;
        x = x * x % MOD;
    }
    return res;
}
vector<ll> f, fi;
void comb(int n) {
    f.resize(n + 10);
    fi.resize(n + 10);
    f[0] = 1;
    for(ll i = 1; i <= n; i++) {
        f[i] = f[i - 1] * i;
        f[i] %= MOD;
    }
    fi[n] = mpow(f[n], MOD - 2);
    for(ll i = n - 1; i >= 0; i--) {
        fi[i] = fi[i + 1] * (i + 1LL);
        fi[i] %= MOD;
    }
}
ll ncr(ll n, ll r) { return f[n] * fi[r] % MOD * fi[n - r] % MOD; }
ll nhr(ll n, ll r) { return (n == 0 && r == 0) ? 1LL : ncr(n + r - 1, r); }
int main() {
    ll n, m, d1, d2;
    cin >> n >> m >> d1 >> d2;
    ll d = d2 - d1;
    m -= d1 * (n - 1LL) + 1LL;
    ll ans = 0;
    comb(n + m + 10);
    for(ll i = 0; i <= n - 1LL; i++) {
        if(m < i * (d + 1LL)) continue;
        ll s = nhr(n + 1LL, m - i * (d + 1LL)) * ncr(n - 1LL, i) % MOD;
        if(i % 2) {
            ans += MOD - s;
        } else {
            ans += s;
        }
        ans %= MOD;
    }
    cout << ans << endl;
}