#include <algorithm>
#include <cstdio>
using namespace std;

int main(){
    int n,k,s,i,c,res;
    while(1){
        scanf("%d",&n);
        scanf("%d",&k);
        scanf("%d",&s);
        if(!n && !k && !s){break;}
        int t[n],cd[n];
        for(i=0;i<n;i++){cd[i]=i+1;t[i]=0;}
        for(i=0;i<k;i++){t[n-i-1]=1;}    
        res=0;
        do{
            c=0;
            for(i=0;i<n;i++){c+=(t[i]*cd[i]);}
            if(c==s){res++;}
        } while(next_permutation(t,t+n));
        printf("%d\n",res);
    }
    return 0;
}

