#include<iostream>
using namespace std;

int n, s, k;
long long f[101][20001];

long long F(int N, int M) {
	if (N < 0 || M < 0)
		return 0;
	return f[N][M];
}

int main() {
	cin >> n >> s >> k;
	s -= k * n * (n - 1)/2;
	
	f[0][0] = 1;
	for( int N = 1; N <= n; N++ ){	//残り項数
		for( int M = 0; M <= s; M++ ){	//残り値
			f[N][M] = F(N, M-N) + F(N-1, M);
			f[N][M] %= 1000000007;
		}
	}
	cout << F(n, s) << endl;
	return 0;
}