import java.util.*;

public class Main {
    private static final Scanner scn = new Scanner(System.in);
    
    public static void main(String[] args) {
        String str;
        while(true) {
            str = scn.next();
            if(str.length() == 1 && str.charAt(0) == '0') {
                break;
            }
            System.out.println(calcSum(str));
        }
    }
    
    public static int calcSum(String str) {
        int c = 0;
        char[] ary = str.toCharArray();
        for(char elm : ary) {
            c += Integer.parseInt(elm + "");
        }
        return c;
    }
}
/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