import java.util.Scanner;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        outer:
        while (true) {

            String line = sc.next();

            int t;
            int sum = 0;

            for (int i = 0; i < line.length(); i++) {

                t = line.charAt(i) - '0';
                sum += t;

                if (sum == 0) {
                    break outer;
                }
            }
            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