input: from typing import List
  
  
  def first_non_repeating_char(lst: List[int]) -> int:
      """ Find the first non-repeating element in the given list.
      >>> first_non_repeating_char([1, 2, 3, 4, 4, 3, 2, 1])
      None
      """
output:     count_dict = {}
      for num in lst:
          if num in count_dict:
              count_dict[num] += 1
          else:
              count_dict[num] = 1
      
      for num in lst:
          if count_dict[num] == 1:
              return num
      
      return None