import java.util.Scanner;

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);

		while (true)
		{
			String num = sc.next();
			if (num.equals("0"))
			{
				return;
			}

			int sum = 0;
			for (int i = 0; i < num.length(); i++)
			{
				sum += (num.charAt(i) - '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