#include<iostream>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstdio>
#define loop(i,a,b) for(int i=a;i<b;i++)
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define it ::iterator
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double ESP=1e-10;
using namespace std;
int n,k,s,co;
void f(int a,int c,int sum){
  if(c==n){
    if(sum==s)co++;
    return;
  }
  loop(i,a,k+1){
    if(sum+i>s)break;
    f(i+1,c+1,sum+i);
  }
}
int main(){
  while(cin>>k>>n>>s,n+k+s){
    co=0;
    f(1,0,0);
    cout<<co<<endl;
  }
}