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;
			}

			// strArry????????????????????????????´?
			String[] strArry = str.split("");

			
			int x = 0;
			int sum = 0;
			for (int i = 0; i < strArry.length; i++) {
				//??´??°???????????????x?????£??\
				x = Integer.parseInt(strArry[i]);
				sum = sum + x;
			}
			
			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