#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <map>
#include <cmath>
#include <queue>
#include <iomanip>
#include <set>
#include <climits>
using namespace std;

const int p {1000000007};

int main() {
    int n, s, k, dp[20001] {};
    cin >> n >> s >> k;
    dp[0] = 1;
    s -= (n - 1) * n / 2 * k;
    if (s < 0) {
        cout << "0\n";
        return 0;
    }
    for (int i = 0; i < n; ++i) {
        for (int j = n - i; j <= s; ++j) {
            dp[j] = (dp[j-(n-i)] + dp[j]) % p;
        }
    }
    cout << dp[s] << '\n';
}