import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		@SuppressWarnings("resource")
		Scanner scan = new Scanner(System.in);

		while (true) {
			String ins = scan.nextLine();
			if (ins.equals("0"))
				break;
			int ans = 0;
			for (int i = 0; i < ins.length(); i++)
				ans += (int) (ins.charAt(i) - '0');
			System.out.println(ans);
		}

		System.exit(0);
	}

}
/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