import java.util.Scanner;

public class Main {

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            char[] c = sc.nextLine().toCharArray();
            if(c[0] == '0') break;
            int sum = c[0] - '0';
            for(int i = 1,l = c.length;i < l;++i) sum += c[i] - '0';
            System.out.println(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