text: from typing import Tuple
  
  
  class errorEmptyInput(Exception):
      pass
  
  
  class errorNotTwoOperands(Exception):
      pass
  
  
  def string_sum(
      user_input: str,
  ) -> Tuple[str, None | errorEmptyInput | errorNotTwoOperands]:
      digit_count = lambda user_input: len([d for d in user_input if d.isdecimal()])
      if user_input.strip() == "" or digit_count(user_input) == 0:
          # raise errorEmptyInput
          return "", errorEmptyInput
      elif digit_count(user_input) != 2:
          # raise errorNotTwoOperands
          return "", errorNotTwoOperands
      else:
          try:
              # replace all whitespace characters from string
              user_input = "".join(user_input.split())
              result = eval(user_input)
          except Exception as e:
              return "", e
          else:
              return result, None
  
  
  def main() -> None:
      user_input = input()
      result, err = string_sum(user_input)
      print(result, err)
  
  
  if __name__ == "__main__":
      main()
  