#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;
  
  int res = s-k*(n-1)*n/2;
  if(res<0){
    cout << 0 << endl;
    return 0;
  }
  
  vector<vector<int>> dp(102,vector<int>(20002));
  dp[0][0] = 1; 
  
  rep(i,n) rep(j,res+1){
    if(i) dp[i][j] = dp[i-1][j];
    if(j-i-1>=0){
      dp[i][j] += dp[i][j-i-1];
      dp[i][j] %= mod;
    }
  }
  
  cout << dp[n-1][res];
}