#include <bits/stdc++.h>
using namespace std;

const int mod = 1e9 + 7, N = 1e6 + 5;

int n, s, k, dp[N];

int main()
{
	cin >> n >> s >> k;
	long long tmp = 1LL * k * n * (n - 1) / 2;
	if (tmp > s)
	{
		cout << 0 << "\n";
		return 0;
	}
	int m = s - tmp;
	dp[0] = 1;
	for(int i = 1; i <= n; i ++ )
		for(int j = i; j <= m; j ++ ) dp[j] = (dp[j - i] + dp[j]) % mod;
	cout << dp[m] << "\n";
	return 0;
}