#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
using ll = long long;
using P = pair<int,int>;
ll M = 1000000007;
int main() {
    int N, S, K; cin >> N >> S >> K;
    int S0 = (N-1)*K*N/2;
    auto dp = vector(N+1, vector<ll>(S+1, 0));
    int T = S - S0;
    if (T < 0) {
        cout << 0 << endl;
        return 0;
    }
    assert(T >= 0);
    dp[0][0] = 1;
    for (int i = 1; i <= N; i++) {
        for (int j = 0; j <= T; j++) {
            if (0 <= j-i) {
                dp[i][j] = (dp[i][j-i] + dp[i-1][j]) % M;
            } else {
                dp[i][j] = dp[i-1][j];
            }
        }
    }
    ll ans = dp[N][T];
    cout << ans << endl;
    return 0;
}