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


class Main{
	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		while(true){
			String str=br.readLine();
			if(str.equals("0"))break;
			int t=0;
			for(int i=0;i<str.length();i++){
				t+=Character.getNumericValue(str.charAt(i));
			}System.out.println(t);
		}
		}}
/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