import java.util.Scanner;

class Main {
  static Scanner in = new Scanner(System.in);
  public static void main(String[] args) {
    
    while(in.hasNext()){
      int sum = 0;
      String input = in.next();
      if (input.equals("0")) break;
      for (int i = 0; i < input.length(); i++) sum += input.charAt(i) - '0';
      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