import java.util.Scanner;

public class Main {
	public static void main(String [] args) {
		Scanner scan = new Scanner(System.in);
		int sum;
		String x;
		
		do {
			
			x = scan.nextLine();
					
			if(x.equals("0"))break;
			sum = 0;
			
			for(int i = 0; i < x.length(); i++) {
				char c = x.charAt(i);
				sum += (int)c - 48;
			}
			
			System.out.println(sum);
			
		}while(true);
	}
}


/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