#include <iostream>
#include <algorithm>
#include <vector>
#define MOD 1000000007;
using namespace std;
int n, m;
long long dp[101][20001];
int main() {
	cin.tie(0);ios::sync_with_stdio(false);
	int n, N, S, K;cin >> N >> S >> K;
	n = S - N*(N - 1) / 2 * K;
	m = N;

	dp[0][0] = 1;
	for (int i = 1; i <= m; i++) {
		for (int j = 0; j <= n;j++) {
			if (j - i >= 0) {
				dp[i][j] = (dp[i - 1][j] + dp[i][j - i]) % MOD;
			}
			else {
				dp[i][j] = dp[i - 1][j];
			}
		}
	}

	cout << dp[m][n] << endl;
}