SumDigits

import java.util.Scanner;

public class P02SumDigits {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        int n = Integer.parseInt(scanner.nextLine());

        int sum = 0;

        do {
            sum = sum + (n % 10);
            n = n /10;

        }

        while (n>0);

        System.out.println("" + sum);

    }
}