import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {


		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));


		for(;;){

			int sum =0;

			String[] input = br.readLine().split("");

			if(input[0].equals("0")){break;}

			for(int i=0;i<input.length;i++){

				sum += Integer.parseInt(input[i]);


			}System.out.println(sum);



		}



		//??????

	}
}
/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