import java.util.Scanner;
import java.lang.Integer;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String intStr = s.replaceAll("[^0-9]","");
        Integer number = Integer.valueOf(intStr);
        System.out.println(sumDigits(number));
    }
    
    public static int sumDigits(int n) {
        int sum = 0;
        while (n != 0) {
            sum += n % 10;
            n /= 10;
        }
        return sum;
    }
}