问题 1072: 汽水瓶

import java.util.Scanner;

public class Prog1072 {

public static void main(String[] args) {

Scanner scan = new Scanner(System.in);

while (scan.hasNext()) {

int n = scan.nextInt();

if (n == 0) {

break;

}

int sum = 0;

while (n != 0) {

sum += n / 3;

n = n % 3 + n / 3;

if (n == 2) {

sum++;

break;

}

if (n < 2)

break;

}

System.out.println(sum);

}

}

}