#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

using mint = modint1000000007;

void debug_mint1(vector<mint> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        cerr << vec[i].val() << " ";
    }
    cerr << endl;
}

void debug_mint2(vector<vector<mint>> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        for (int j = 0; j < vec[i].size(); j++) {
            cerr << vec[i][j].val() << " ";
        }
        cerr << endl;
    }
}

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

    ll coef = M - 1 - D1 * (N - 1);
    if (coef < 0){
        cout << 0 << endl;
        return 0;
    }

    vector<mint> fact(1000002);
    fact[0] = mint(1);
    for (ll i = 0; i < 1000001; i++){
        fact[i + 1] = fact[i] * mint(i + 1);
    }

    vector<mint> finv(1000002);
    for (ll i = 0; i < 1000002; i++){
        finv[i] = mint(1) / fact[i];
    }

    auto comb = [&fact, &finv](ll n, ll r) -> mint{
        if (n < r){
            return mint(0);
        }
        else if (r < 0){
            return mint(0);
        }
        return fact[n] * finv[n - r] * finv[r];
    };

    // 二項定理
    vector<mint> pos(M + 1, 0);
    for (ll i = 0; i <= N - 1; i++){
        ll pr = (D2 - D1 + 1) * i;
        if (pr > M){
            break;
        }
        pos[pr] = comb(N - 1, i);
        if (i % 2 == 1){
            pos[pr] *= mint(mod1 - 1);
        }
    }

    vector<mint> neg(M + 1, 0);
    for (ll i = 0; i < M + 1; i++){
        neg[i] = comb(i + N, N);
    }
    // debug(coef);
    // debug_mint1(pos);
    // debug_mint1(neg);
    mint ans = 0;
    for (ll i = 0; i <= coef; i++){
        ans += pos[i] * neg[coef - i];
    }
    cout << ans.val() << endl;
}