/* -*- coding: utf-8 -*-
 *
 * 269.cc: No.269 見栄っ張りの募金活動 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100;
const int MAX_S = 20000;
const int MAX_K = 100;

typedef long long ll;
const ll MOD = 1000000007;

/* typedef */

/* global variables */

ll dp[2][MAX_S + 1];

/* subroutines */

/* main */

int main() {
  int n, s, k;
  cin >> n >> s >> k;

  s -= k * n * (n - 1) / 2;
  if (s < 0) {
    puts("0");
    return 0;
  }

  dp[0][0] = 1;
  int cur = 0, nxt = 1;

  for (int i = 0; i < n; i++) {
    memcpy(dp[nxt], dp[cur], sizeof(dp[0]));

    int ci = n - i, c = ci;
    while (c <= s) {
      int maxj = s - c;
      for (int j = 0; j <= maxj; j++)
	dp[nxt][j + c] = (dp[nxt][j + c] + dp[cur][j]) % MOD;
      c += ci;
    }

    cur ^= 1, nxt ^= 1;
  }

  printf("%lld\n", dp[cur][s]);
  return 0;
}