import java.util.Scanner;

public class Main 
{
	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);
		
		for(;;)
		{
			String in = scanner.next();
			//String out = "";
			if(in.equals("0"))
			{
				break;
			}
			
			int sum = 0;
			for(int i=0; i<in.length(); i++)
			{
				char c = in.charAt(i);
				sum += c - '0';
			}
			
			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