HJ22 汽水瓶

import java.util.*;
import java.io.*;
public class Main{
    
    public static void main(String[] args) throws IOException{
    
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String str="";
        while(!(str=br.readLine()).equals("0")){
    
            Box box=new Box(0,Integer.parseInt(str));
            System.out.println(checkBox(box).drinkBox);
        }
    }
    public static Box checkBox(Box box){
    
        if (box.emptyBox<2){
    
            return box;
        }else if (box.emptyBox==2){
    
           box.drinkBox++;
           box.emptyBox=0;
           return box;
        }else{
    
            box.drinkBox=box.drinkBox+box.emptyBox/3;
            box.emptyBox=box.emptyBox%3+box.emptyBox/3;
            Box box1 = checkBox(box);
            return box1;
        }
    }
    
    static class Box{
    
        private Integer drinkBox;
        private Integer emptyBox;

        public Box(int drinkBox,int emptyBox){
    
            this.drinkBox=drinkBox;
            this.emptyBox=emptyBox;
        }
    }
}