#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "unordered_map"
#include "unordered_set"
#include "iomanip"
#include "cmath"
#include "random"
#include "bitset"
#include "cstdio"
#include "numeric"
#include "cassert"

using namespace std;

const long long int MOD = 1000000007;
//const int MOD = 998244353;

//long long int N, M, K, H, W, L, R;
int N, M, K, H, W, L, R;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> N >> M >> L >> R;
	K = M - (N - 1)*L;
	if (K < 0) {
		cout << 0 << endl;
		return 0;
	}
	vector<int>dp(K + 1);
	dp[0] = 1;
	for (int i = 1; i < N; i++) {
		for (int j = K; j >= 0; j--) {
			for (int k = R - L; k > 0; k--) {
				if (j - k >= 0) {
					dp[j] += dp[j - k];
					dp[j] %= MOD;
				}
			}
		}
	}
	int ans = 0;
	long long int cnt = K;
	for (auto i : dp) {
		int add = (cnt*i) % MOD;
		ans += add;
		ans %= MOD;
		cnt--;
	}
	cout << ans << endl;
	return 0;
}