#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pdd = pair<ld, ld>;
using pll = pair<ll, ll>;
using pli = pair<ll, int>;
using pil = pair<int, ll>;
template <typename T>
using Graph = vector<vector<T>>;
const int MOD = 1e9 + 7;
const ld PI = acos(-1);

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int N, S, K;
    cin >> N >> S >> K;
    int tmp = N * (N - 1) / 2 * K;
    if (S < tmp) {
        cout << 0 << endl;
        return 0;
    }

    S -= tmp;
    vector<vector<int>> dp(N + 1, vector<int>(S + 1));
    dp[0][0] = 1;
    for (int i = 0; i < N; ++i) {
        for (int j = 0; j <= S; ++j) {
            int k = N - i;
            if (j >= k) {
                (dp[i][j] += dp[i][j - k]) %= MOD;
            }
            (dp[i + 1][j] += dp[i][j]) %= MOD;
        }
    }

    cout << dp[N][S] << endl;

    return 0;
}