#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using pii = pair<int, int>;

const int mod = 1e9 + 7;
int N, S, K;
int dp[101][20010];

int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(10);
  
  cin >> N >> S >> K;
  dp[0][0] = 1;
  for (int i = 1; i <= N; i++) {
    for (int j = 0; j <= S; j++) {
      dp[i][j] = dp[i - 1][j];
      if (j - i >= 0) {
        (dp[i][j] += dp[i][j - i]) %= mod;
      }
    }
  }
  
  int sum = S - K * N * (N - 1) / 2;
  cout << (sum < 0 ? 0 : dp[N][sum]) << endl;

  return 0;
}