import java.util.Scanner;

public class Main {
	 public static void main(String[] args) {
		 Scanner sc = new Scanner(System.in);
		 while(true){
			 String x=sc.nextLine();
			 if(x.equals("0"))break;
			 int sum=0;
			 for (char y:x.toCharArray()) {
				 sum +=Integer.parseInt(String.valueOf(y));
			 }

		 System.out.println(sum);
		 }
		 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