import java.util.Scanner;

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

        while(sc.hasNext()) {
            String box = sc.next();

            if (box.equals("0"))
                break;

            int sum = 0;
            for(int i=0; i<box.length(); i++){
                sum+=box.charAt(i)-'0';
            }
            System.out.printf("%d\n",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