import java.util.Scanner;

public class Main {
    public static void main(String... args) {
        Scanner sc = new Scanner(System.in);

        while(true) {
        	String str = sc.next();
        	int sum = 0;

        	if(str.equals("0")) {
        		break;
        	}

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

        	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