import java.util.Scanner;


public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		while(true){
			String x = scan.next();
			if(x.equals("0")){
				break;
			}
			int sum = 0;
			for(int i = 0; i < x.length(); i++){
				sum += Character.digit(x.charAt(i), 10);
			}
			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