import java.util.Scanner;

public class Main{
	public static void main(String args[]){

		Scanner sc = new Scanner(System.in);
		while(true){

			//1??????????????????
			String s = sc.nextLine();

			if(s.equals("0")){
				break;
			}


			char [] cha = s.toCharArray();
			int sum = 0;

			for(int i = 0; i < cha.length; i++){
				//System.out.println(cha[i]);
				sum += Character.getNumericValue(cha[i]);
			}

			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