import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true) {
            String num = sc.next();
            int i;
            int Sum = 0;
            for (i = 0; i <= (num.length() - 1); i++) {
                int x = ((num.charAt(i)) - '0');
                Sum += x;
            }
            if(Sum == 0) break;
            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