import java.util.*;

public class Main{
	private static final Scanner scan = new Scanner(System.in);

	public static void main(String[] args){
		List<Integer> list = new ArrayList<Integer>();
		for(;;){
			String number = scan.next();
			if(number.equals("0")){
				break;
			}
			int sum = 0;
			for(int i = 0; i < number.length(); i++){
				char ch = number.charAt(i);
				String c = String.valueOf(ch);
				int n = Integer.parseInt(c);
				sum += n;
			}
			list.add(sum);
		}

		for(int n : list){
			System.out.println(n);
		}
	}
}
/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