import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
		while(true){
            String x = sc.next();
			int ans = 0;
			if(x.equals("0")){
				break;
			}else{
				for(int i=0; i<x.length(); i++){
					ans += Integer.parseInt(String.valueOf(x.charAt(i)));
				}
			}
			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