#include <iostream>
#include <cmath>

#define ll long long int

using namespace std;

const int mod = 1e9 + 7;

int dp[20001][101];

int main(int argc, char const* argv[])
{
	int n, s, k;
	cin >> n >> s >> k;
	s -= k * (n - 1) * n / 2;
	if(s < 0){
			cout << 0 << endl;
			return 0;
	}
	for(int i = 0; i <= n; i++)dp[0][i] = 1;
	for(int i = 1; i <= s; i++){
			for(int j = 1; j <= n; j++){
					if(i >= j)dp[i][j] = int(((ll)dp[i-j][j] + (ll)dp[i][j-1]) % mod);
					else dp[i][j] = dp[i][j-1];
			}
	}
	cout << dp[s][n] << endl;
	return 0;
}