UVALive 6661 Equal Sum Sets

 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <algorithm>
 #include <string>
 #include <vector>
 #include <map>
 #include <set>
 #include <time.h>
 #include <queue>
 #include <stack>
 #include <cctype>
 #include <utility>
 #include <numeric>
 #include <cstdlib>
 #include <functional>
 #include <iomanip>
 #include <sstream>
 using namespace std;
 int n,k,s;
 int ans;
 void gao(int now,int deep,int sum)
 {
   if(deep==k&&sum==s) {ans++;return ;}
   if(deep>k||sum>s) return ;
   else
     for(int i=now+;i<=n;i++)
       gao(i,deep+,sum+i);
   return ;
 }
 int main()
 {

   while(scanf("%d%d%d",&n,&k,&s)!=EOF)
   {
     if(n+k+s==) break;
     ans=;
     for(int i=;i<=n;i++)
       gao(i,,i);
     printf("%d\n",ans);
   }
   return ;
 }