import java.util.Scanner;
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    int sum = 0;

    for(int i = 0; i<s.length(); i++) {
      char a = s.charAt(i);
      switch(a){
        case('1'):
          sum += 1;
          break;
        case('2'):
          sum += 2;
          break;
        case('3'):
          sum += 3;
          break;
        case('4'):
          sum += 4;
          break;
        case('5'):
          sum += 5;
          break;
        case('6'):
          sum += 6;
          break;
        case('7'):
          sum += 7;
          break;
        case('8'):
          sum += 8;
          break;
        case('9'):
          sum += 9;
      }
    }
    System.out.println(sum);
  }
}