
import java.util.Scanner;

public class Main {
	public static void main(String[] args)
	{
		Scanner stdIn = new Scanner(System.in);
		
		while(true)
		{
			String str = stdIn.next();
			
			if(str.charAt(0) == '0')
			{
				break;
			}
			
			int ans = 0;
			
			for(int i=0;i<str.length();i++)
			{
				ans += (int)str.charAt(i)-48;
			}
			
			System.out.println(ans);
			
		}
	}
}
/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