题解 | #汽水瓶#,刚开始把作用域搞混了，每次没有把换取的和统计的清零。。

import java.util.ArrayList;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        ArrayList<Integer> list = new ArrayList<>();
        while (true) {
            int n = scanner.nextInt();
            if (n == 0) {
                break;
            }
            list.add(n);
        }

        ArrayList<Integer> result = new ArrayList<>();
        for (int i = 0; i < list.size(); i++) {
            int kp = list.get(i);
            int hq = 0;
            int count = 0;
            if (kp < 2) {
                result.add(hq);
                continue;
            }
            while (true) {
                if (kp == 2) {
                    result.add(count + 1);
                    break;
                }else if (kp < 2){
                    result.add(count);
                    break;
                }
                hq = kp / 3;
                count += hq;
                kp = (kp - 3 * hq) + hq;
            }

        }
        for (int i = 0; i < result.size(); i++) {
            System.out.println(result.get(i));
        }
    }
}