import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            String s = sc.next();
            if (s.equals("0")) {
                break;
            }
            System.out.println(digitSum(s));
        }
    }

    private static int digitSum(String num) {
        int sum = 0;
        for (int i = 0; i < num.length(); i++) {
            sum += Integer.parseInt(String.valueOf(num.charAt(i)));
        }
        return 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