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

public class Main {
	
	public static void main(String[] args) {
		try {
			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
			
			String input;
			for (;;) {
				input = reader.readLine();
				if (input.equals("0")) break;
				char ch;
				int sum = 0;
				for (int i = 0; i < input.length(); i++) {
					ch = input.charAt(i);
					sum += Character.getNumericValue(ch);
				}
				System.out.println(sum);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}
/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