import java.io.*;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String s = in.readLine();
		
		while(!s.equals("0")){
			int num = 0;
			for(int i = 0; i < s.length(); i++){
				num += Integer.parseInt(s.substring(i, i+1));
			}
			System.out.println(num);
			s = in.readLine();
		}
	}

}
/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