import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    int res = 0;
    for  (int i = 0; i  < s.length(); i++) {
      try {
          res += Integer.valueOf(s.substring(i, i+1));
      } catch (NumberFormatException e) {    
      }
    }
    System.out.println(res);
  }
}