#include<bits/stdc++.h>
using namespace std;
int n,s,k;
int memo[101][20001];
int solve(int idx,int nokori){
  if(nokori < 0) return 0;
  if(idx == 1) return 1;
  if(memo[idx][nokori] != -1) return memo[idx][nokori];

  int ret;
  ret = (solve(idx-1,nokori) + solve(idx,nokori-idx)) % 1000000007;
  return memo[idx][nokori] = ret;
}
int main(){
  cin>>n>>s>>k;
  memset(memo,-1,sizeof(memo));
  s -= k*n*(n-1)/2;
  cout<<solve(n,s)<<endl;
  return 0;
}