import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        char[] carr = s.toCharArray();
        int count = 0;
        int answer;
        for(char c:carr){
            if(c=='0')
            count++;
        }
        if(count<8)
        answer = 8-count;
        else
        answer = count-8;
        System.out.println(answer);
    }
}