#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int ans,n,k,s;
int used[21];
void dfs(int d,int sum,int t){
    if(sum==s&&d==0){ans++;return;}
    else if(d==0) return ;
    for(int i=t+1;i<=n;i++){
        if(!used[i]){
            used[i]=1;
            dfs(d-1,sum+i,i);
            used[i] =0;
        }
    }
}
int main()
{
    while(cin >> n >> k >>s&&n){
        memset(used,0,sizeof(used));
        ans = 0;
        dfs(k,0,0);
        cout << ans << endl;
    }
    return 0;
}

 