package algorithm.huawei;

import java.util.Scanner;

/**

* @Author: eric

* @Date: 2022/4/23 11:03 上午

*/

public class Tea01 {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

String[] str = in.nextLine().split(",");

String s = "";

for (String st : str) {

s += st;

}

String[] newStr = s.split("0");

int count = 0;

for (int i = 0; i < newStr.length; i++) {

int length = newStr[i].length();

if (length == 0) {

continue;

}

if (length % 3 != 0) {

count += (length - length % 3) / 3 + 1;

} else {

count += length / 3;

}

}

System.out.println(count);

}

}