题解 | #汽水瓶#

#include <iostream>
using namespace std;

int main() {
   int bow;
   while(cin>>bow){
    if(bow==0)break;
    int count=0;
    
   
    while(bow>2){
        count+=bow/3;
        bow=bow/3+bow%3;
    }
    if(bow==2)count++;
    cout<<count<<endl;
    }

}
// 64 位输出请用 printf("%lld")