import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		while (s.hasNext()) {
			char[] chars = s.next().toCharArray();
			if (chars[0] == '0') return;
			int sum = 0;
			for (int i = 0; i < chars.length; ++i) {
				sum += Character.getNumericValue(chars[i]);
			}
			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