import java.util.*;

class Main {
        public static void main(String args[]) {
                try (Scanner sc = new Scanner(System.in)) {
                        while (true) {
                                String S = sc.next();
                                if (S.equals("0")) {
                                        break;
                                }
                                long ans = 0;
                                for (int i = 0; i < S.length(); i++) {
                                        ans += S.charAt(i) - '0';
                                }
                                System.out.println(ans);
                        }
                }
        }
}
/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