import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            String s = sc.next();

            if (s.length() == 1 && s.charAt(0) == '0')
                break;

            int sum = 0;

            for (int i = 0; i < s.length(); i++)
                sum += Character.digit(s.charAt(i), 10);

            System.out.println(sum);
        }

    }
}


/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz