code: 
  
  from __future__ import annotations
  
  
  
  class   __lowerCamelCase :
  
  
  
  
  
  
  
         def __init__( self:   Any,A_:   int				):
  
  
  
  
  
  
              '''simple docstring'''
  
  
  
  
              __UpperCamelCase   = data
              __UpperCamelCase   = None
  
  
  
  class   __lowerCamelCase :
  
  
  
  
  
  
  
         def __init__( self:   Optional[int]				):
  
  
  
  
  
  
              '''simple docstring'''
  
  
  
  
              __UpperCamelCase   = None
  
  
  
  
  
  
  
         def 		snake_case_  ( self:   Union[str, Any],A_:   int				):
  
  
  
  
  
  
              '''simple docstring'''
  
  
  
  
              __UpperCamelCase   = Node(A_				)
              __UpperCamelCase   = self.head
              __UpperCamelCase   = new_node
              return self.head.data
  
  
  
  
  
  
  
         def 		snake_case_  ( self:   List[str]				):
  
  
  
  
  
  
              '''simple docstring'''
  
  
  
  
              __UpperCamelCase   = self.head
              __UpperCamelCase   = self.head
              if self.head:
                   while fast_pointer and fast_pointer.next:
                        __UpperCamelCase   = fast_pointer.next.next
                        __UpperCamelCase   = slow_pointer.next
                   return slow_pointer.data
              else:
                   print('No element found.'				)
                   return None
  
  
  if __name__ == "__main__":
      __snake_case             =	LinkedList()
      for _ in range(int(input().strip())):
          __snake_case             =	int(input().strip())
          link.push(data)
      print(link.middle_element())
  
  
  
style_context: 
  
  
  def 		_A		(		_lowercase   )				->   bool:
  
  
       """simple docstring"""
  
  
       if not isinstance(_lowercase				,     _lowercase   ):
            raise ValueError('Input series is not valid, valid series - [1, 2/3, 2]'   )
       if len(_lowercase   ) == 0:
            raise ValueError('Input list must be a non empty list'   )
       if len(_lowercase   ) == 1 and series[0] != 0:
            return True
       __UpperCamelCase   = []
       __UpperCamelCase   = len(_lowercase   )
       for i in range(0				,     _lowercase   ):
            if series[i] == 0:
                 raise ValueError('Input series cannot have 0 as an element'   )
            rec_series.append(1 / series[i]   )
       __UpperCamelCase   = rec_series[1] - rec_series[0]
       for index in range(2				,     _lowercase   ):
            if rec_series[index] - rec_series[index - 1] != common_diff:
                 return False
       return True
  
  
  
  
  
  
  def 		_A		(		_lowercase   )				->   float:
  
  
       """simple docstring"""
  
  
       if not isinstance(_lowercase				,     _lowercase   ):
            raise ValueError('Input series is not valid, valid series - [2, 4, 6]'   )
       if len(_lowercase   ) == 0:
            raise ValueError('Input list must be a non empty list'   )
       __UpperCamelCase   = 0
       for val in series:
            answer += 1 / val
       return len(_lowercase   ) / answer
  
  
  if __name__ == "__main__":
      import doctest
  
      doctest.testmod()
  
  
  