import java.util.*;
import java.text.*;

class Main {
    public static void main(String[]args)throws Exception {
        Scanner sc = new Scanner(System.in);
        for(;;) {
            char [] cs = sc.nextLine().toCharArray();
            if(cs[0] == '0') break;
            int s = 0;
            for(int i = 0; i < cs.length; i++) {
                s += cs[i] - '0';
            }
            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