题解 | #汽水瓶#

import java.util.*;
import java.io.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
       BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
            String s;
            while (!"0".equals((s = br.readLine()))){
                int a=Integer.valueOf(s);
                int num;
                int b=0;
                while (a!=1){
                    if(a==2){
                        a=a-1;
                        b++;
                        continue;
                    }
                    num = a%3;
                    b+=a/3;
                    a=a/3 + num;
                }
                System.out.println(b);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}