#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

ll mod=1e9+7;

int main() {
  ll n,s,k;
  cin >> n >> s >> k;
  s-=n*(n-1)*k/2;
  if(s<0) {
    cout << 0 << endl;
    return 0;
  }
  vector<vector<ll>> dp(n+1,vector<ll>(s+1,0));
  dp[0][0]=1;
  for(int i=1;i<=n;i++) {
    for(int j=0;j<=s;j++) {
      if(j-i>-1) {
        dp[i][j]=(dp[i-1][j]+dp[i][j-i])%mod;
      }
      else {
        dp[i][j]=dp[i-1][j];
      }
    }
  }
  cout << dp[n][s] << endl;
}