import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String n = sc.next();
    int a = 0;
    for(int i = 0; i < n.length(); i++) {
      if(n.charAt(i) == '0') a++;
    }
    System.out.println(Math.abs(a - 8));
  }
}