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

public class Main {

	public static final int BIG_NUM  = 2000000000;
	public static final int MOD  = 1000000007;

	public static void main(String[] args) {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int ans;

		while(true){

			try {
				String inputed = br.readLine();
				if(inputed.length() == 1 && inputed.equals("0"))break;

				ans = 0;
				for(int i = 0; i < inputed.length(); i++){
					ans += inputed.charAt(i)-'0';
				}

				System.out.printf("%d\n", ans);

			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}

/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