import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner scan=new Scanner(System.in);
		
		while(true){
			String str=scan.next();
			if(str.equals("0"))break;
			
			int cnt=0;
			for(int i=0;i<str.length();i++)
				cnt+=(str.charAt(i)-'0');
			
			System.out.println(cnt);
			
		}
		
	}
}

/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