import java.util.*;
class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		String x;
		int total;
		while(true){
			x = sc.next();
			if (x.equals("0")){
				break;
			}
			total = 0;
			for (int i = 0; i < x.length(); i++){
				total += Integer.parseInt("" + x.charAt(i));
			}
			System.out.println(total);
		}
	}
}
/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