#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define irep(i, n) for (int i = (n); i >= 0; i--)
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = 1 << 25;
const int MOD = 1e9+7;
int dp[101][20001];
int main() {
	int n,s,k;
	cin >> n >> s >> k;
	int rem = s - k*n*(n-1)/2;
	if (rem < 0) {
		cout << 0 << endl;
		return 0;
	}
	dp[0][0] = 1;
	for (int i = 1; i <= n; i++)
	{
		for (int j = 0; j <= rem; j++)
		{
			if (j>=i) {
				dp[i][j] = (dp[i][j-i]+dp[i-1][j]) % MOD;
			} else {
				dp[i][j] = dp[i-1][j];
			}
		}
		
	}
	cout << dp[n][rem] << endl;
	return 0;
}