#include<bits/stdc++.h>
#pragma warning(disable:4996)
using namespace std;
using ll = long long;
const int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int main() {
	int N, S, K;
	cin >> N >> S >> K;
	vector<vector<int>>dp(N+1, vector<int>(S - (N * (N - 1)*K / 2) + 1, 0));
	dp[0][0] = 1;
	for (int i = 1; i <= N;i++) {
		for (int j = 0; j <= S - (N * (N - 1)*K / 2);j++) {
			if (j - i >= 0) {
				dp[i][j] = dp[i - 1][j] + dp[i][j - i];
			}
			else {
				dp[i][j] = dp[i - 1][j];
			}
		}
	}
	cout << dp[N][S - (N * (N - 1)*K / 2)] << endl;
}