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

public class Main {

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

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

		// ???????????\???????????????????????°??????????¨??????????????????????
		int digits_sum;

		while (true) {

			// ???????????\???
			String num = input.readLine();

			// ????????????????????????
			if (num.equals("0")) {

				break;

			}

			// int???????????????????????\????????????String????????°?????§????´?
			char[] digits_number_array = num.toCharArray();

			// ?????????????????°?????????????????????
			int d_line_num = digits_number_array.length;

			// ?????????sum????¶????????????????
			digits_sum = 0;

			// ??\??????????????°?????????????????????????¶???????????????????
			for (int digits_number_spot = 0; digits_number_spot < d_line_num; digits_number_spot++) {

				// char???int??????????????¨??§????¶??????????????????????
				int digits_num = Character.getNumericValue(digits_number_array[digits_number_spot]);


				// ???????????°???????¶???????????????????
				digits_sum += digits_num;

			}

			System.out.println(digits_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