import java.util.Scanner;

public class Main {

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

		StringBuffer line = new StringBuffer(sc.nextLine());
		for (; !line.toString().equals("0");) {
			int sum = 0;
			for (int i = 0; i < line.length(); i++) {
				char ch = line.charAt(i);
				sum += ch - '0';
			}
			System.out.println(sum);
			
			line = new StringBuffer(sc.nextLine());
		}
		
		sc.close();
	}
}
/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