import java.io.IOException;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws IOException {
	Character objChar1;
	String str;
	char c;
	int i,num,sum;
	Scanner scan = new Scanner(System.in);
	while(true) {
	str=scan.next();
	if(str.equals("0"))
		break;
	sum=0;

	for (i=0;i<str.length();i++){
		c=str.charAt(i);
		num=Character.digit(c,10);
		sum+=num;
	}
	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