import java.io.*;
import java.util.*;
 
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;
            char[] c_array=str.toCharArray();
            int sum=0;
            for(char c:c_array) sum+=Integer.parseInt(String.valueOf(c));
            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