#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <functional>
#include <cmath>
#include <string>
#include <queue>
#include <map>
#include <bitset>
#include <set>
#include <stack>
#include <numeric>
#include <unordered_map>
#include <random>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vd = vector<int>;
using vs = vector<string>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<int, int>;
using vpii = vector<pii>;
using vpll = vector<pll>;
using vpdd = vector<pdd>;
const int inf = 1 << 30;
const ll INF = 1LL << 60;
const int MOD = 1000000007;
//const int MOD = 998244353;

int main() {
	int n, s, k;
	cin >> n >> s >> k;
	int sum = n * (n - 1) * k / 2;
	int m = s - sum;
	if (m < 0) {
		cout << 0 << endl;
		return 0;
	}
	vvi dp(n + 1, vi(m + 1, 0));
	dp[0][0] = 1;
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j <= m; j++) {
			if (j - i >= 0) {
				dp[i][j] = dp[i - 1][j] + dp[i][j - i];
				dp[i][j] %= MOD;
			}
			else {
				dp[i][j] = dp[i - 1][j];
			}
		}
	}
	cout << dp[n][m] << endl;

	return 0;
}