import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		long num, length;
		long ans;
		int i = 0, a = 0;
		String b;
		char c;
		Scanner sc = new Scanner(System.in);
		while (true) {
			ans = 0;
			b = sc.nextLine();
			// System.out.println(b);
			length = b.length();
			if (b.equals("0")) {
				break;
			}
			for (i = 0; i < length; ++i) {
				c = b.charAt(i);
				a = c - '0';
				ans += a;
			}
			System.out.println(ans);
		}
		sc.close();
	}

}


/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