input: from typing import List
  
  def max_of_three(numbers: List[int]) -> int:
      """ Find the maximum of three numbers.
      >>> max_of_three([3, 4, 5])
      5
      >>> max_of_three([7, 12, 9])
      12
      >>> max_of_three([-1, -5, -3])
      -1
      """
output:     return max(numbers)