import java.io.*;

public class Main {
	public static void main(String[] args) {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		try {
			String line;
			while ((line = reader.readLine()) != null) {
				if (line.equals("0"))
					break;
				int sum = 0;
				for (int i = 0; i < line.length(); i++) {
					sum += line.charAt(i) - '0';
				}
				System.out.println(sum);
			}
		} catch (IOException e) {
		}
	}
}
/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