import java.util.*;

public class Main {
	private static Scanner sc=new Scanner(System.in);;

	public static void main(String args[]) {
		//System.out.println((int)'1');
		while(sc.hasNextLine()){
			char a[]=sc.nextLine().toCharArray();
			if(a[0]==48)break;
			int ans=0;
			for(int i=0;i<a.length;i++){

				ans+=a[i]-48;
			}
			System.out.println(ans);
		}
	}
}
/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