题解 | #汽水瓶#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.time.LocalDateTime;
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.Stream;


public class Main {
    public static void main(String[] args) throws IOException {

        //testCompletePack();
        testTh();
    }

    private static void testTh() throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        String str;
        while ((str = bf.readLine()) != null) {
            int parseInt = Integer.parseInt(str);
            if (parseInt == 0)break;
            int res = 0;
            while (parseInt >= 3) {
                res++;
                parseInt = parseInt - 3;
                parseInt++;
            }
            if (parseInt == 2)res++;
            System.out.println(res);
        }
    }

}