#include <bits/stdc++.h>
#define rep(i, a) rep2 (i, 0, a)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) repr2 (i, 0, a)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define asn(a, b, c) fill_n(&(b), sizeof(a) / sizeof(b), c)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

ll N, S, K;
ll dp[111][20202];

int main() {
	cin >> N >> S >> K;
	ll T = S - K * N * (N - 1) / 2;

	dp[0][0] = 1;
	rep2 (i, 1, N + 1) {
		rep (j, T + 1) {
			if (j - i >= 0) {
				dp[i][j] = (dp[i - 1][j] + dp[i][j - i]) % mod;
			} else {
				dp[i][j] = dp[i - 1][j];
			}
		}
	}

	ll ans = dp[N][T];
	cout << ans << endl;

	return 0;
}