import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scn = new Scanner(System.in);
        while(true) {
            String str = scn.next();
            if(str.equals("0")) {
                break;
            }
            int s = 0;
            char[] ary = str.toCharArray();
            for(char elm : ary) {
                s += Integer.parseInt(elm + "");
            }
            System.out.println(s);
        }
    }
}
/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