#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <map>
#include <stack>
#include <queue>
#include <set>
#include <cstring>

using namespace std;
// ascending order
#define vsort(v) sort(v.begin(), v.end())
// descending order
#define vsort_r(v) sort(v.begin(), v.end(), greater<int>())
#define vunique(v) v.erase(unique(v.begin(), v.end()), v.end())
#define mp make_pair
#define ts(x) to_string(x)
#define rep(i, a, b) for(int i = (int)a; i < (int)b; i++)
#define repm(i, a, b) for(int i = (int)a; i > (int)b; i--)
#define bit(a) bitset<8>(a)
#define des_priority_queue priority_queue<int, vector<int>, greater<int> >
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
typedef long long ll;
typedef pair<int, int> P;
const ll INF = 1e18;

#define MAX_V 1000000

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

  int n, s, k;
  cin >> n >> s >> k;
  int mod = 1e9 + 7;
  int diff = n * (n - 1) / 2 * k;
  if(s - diff < 0) {
    cout << 0 << endl;
    return 0;
  }

  int dp[n + 1][s - diff + 1];
  memset(dp, 0, sizeof(dp));
  dp[0][0] = 1;

  rep(i, 1, n + 1) {
    rep(j, 0, s - diff + 1) {
      if(j - i >= 0) {
        dp[i][j] = (dp[i - 1][j] + dp[i][j - i]) % mod;
      } else {
        dp[i][j] = dp[i - 1][j];
      }
    }
  }
  cout << dp[n][s - diff] << endl;
}