public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		java.util.Scanner sc = new java.util.Scanner(System.in);
		StringBuilder sb = new StringBuilder();

		while (true) {

			String data = sc.nextLine();
			if ( data.equals("0") ) break;

			int sum = 0;
			for (int i=0; i < data.length(); i++) {
				sum += Integer.parseInt( data.substring(i, i+1) );
			}

			sb.append(sum + "\n");

		}

		System.out.print(sb);
	}

}
/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