import java.util.*;

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