题解 | #汽水瓶#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner fzhinput = new Scanner(System.in);
        int hddnum,newqspnum;
        while(fzhinput.hasNextLine()){
            hddnum=0;
            newqspnum=0;
            int qspnum = fzhinput.nextInt();
            if(qspnum==0){
                break;
            }
            while(qspnum>=3){
                newqspnum=qspnum/3;

                hddnum+=newqspnum;

                qspnum = qspnum%3+newqspnum;
            }

            if(qspnum==2){
                hddnum++;
            }
            System.out.println(hddnum);
        }
    }
}