import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		for(;;){
			String x = sc.next();
			if(x.equals("0"))break;
			String[] strArray = x.split("");
			int add = 0;
			for (int i = 0; i < strArray.length; i++) {
				int num = Integer.parseInt(strArray[i]);
			    add += num;
			}
			System.out.println(add);
		}
	}	
}
/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