题解 | #汽水瓶#

#include<iostream>
using namespace std;

int main(){
    int bottle =0;
    int a=0 , b=0;
    int sum=0;
    while(cin >> bottle && bottle !=0){
        int sum=0;
        while(bottle>1){
        a = bottle/3;
        b = bottle%3;
        sum += a;
        bottle = a+b;
        if((a+b)==2){
            sum+=1;
            bottle=0;
            }
        }
        cout << sum << endl;
    }
}