import java.util*;

public class Ticket{
  public static void main(String arg[]){
    Scanner sc = new Scanner(System.in);
    int tn = sc.nextInt();
    int a, b, c, d, e, f;
    a = tn / 1000000;
    b = tn / 100000 % 10;
    c = tn / 10000 % 10;
    d = tn / 1000 % 10;
    e = tn / 100 % 10;
    f = tn % 10;
    System.out.println (a + b + c + d + e + f);
  }
}