#include<bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < n; i++)
#define pb push_back
using namespace std;
typedef long long ll;

const int mod=1e9+7;

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