#include <iostream>
#include <vector>
using namespace std;

const int MOD = 1e9 + 7;

int solve(int N, int S, int K){
	int start = K * (N - 1) * N / 2;
	if(start > S){
		return 0;
	}
	S -= start;

	vector<int> dp(S + 1, 0);
	dp[0] = 1;
	for(int i=0;i<N;i++){
		for(int sum=N-i;sum<=S;sum++){
			dp[sum] = (dp[sum] + dp[sum-(N-i)]) % MOD;
		}
	}

	return dp[S];
}

int main(){
	int N, S, K;
	cin >> N >> S >> K;

	cout << solve(N, S, K) << endl;
	return 0;
}