import java.util.*;
class Main {
	public static void main (String[] args) throws java.lang.Exception {
		Scanner sc = new Scanner(System.in);
		while(true) {
			String s = sc.next();
			if(s.equals("0")) break;
			int ret = 0;
			for(int i = 0; i < s.length(); i++) ret += s.charAt(i) - 48;
			System.out.println(ret);
		}
	}
}
/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