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

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String str = br.readLine();
			if ("0".equals(str)) {
				break;
			}
			int len = str.length();
			int sum = 0;
			for (int i = 0; i < len; i++) {
				int n = Integer.parseInt(String.valueOf(str.charAt(i)));
				sum += n;
			}
			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