import java.util.Scanner;
  
class Main{
  public static void main(String[] arg){
    String input;
 
    Scanner in = new Scanner(System.in);

    while(true){
        input = in.nextLine();

        if(input.equals("0")) break;

        int tmp=0;
        for(int i=0; i<input.length(); ++i){
            
            char ch = input.charAt(i);
            tmp += Character.getNumericValue(ch);

        }
        System.out.println(tmp);
    }

  }
}
/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