import java.util.Scanner;

public class Main {
	private static Scanner sc=new Scanner(System.in);
	public static void main(String[] args){
		while(true){
			String str=sc.nextLine();
			if(str.equals("0")) break;
			int[] ch=new int[str.length()];
			int sum=0;
			for(int i=0;i<str.length();i++){
				ch[i]=Character.getNumericValue(str.charAt(i));
				sum=sum+ch[i];
			}
			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