
from math import factorial


def    A (      lowercase = 20				)     ->						int:
		'''simple docstring'''

		UpperCamelCase						=  2 * n  # middle entry of odd rows starting at row 3 is the solution for n = 1,
		# 2, 3,...
		UpperCamelCase						=  n // 2

		return int(factorial(lowercase				) / (factorial(lowercase				) * factorial(n - k				))				)


if __name__ == "__main__":
					import sys

					if len(sys.argv) == 1:
										print(solution(20))
					else:
										try:
															_UpperCAmelCase      :				List[str]          = int(sys.argv[1])
															print(solution(n))
										except ValueError:
															print("Invalid entry - please enter a number.")


import re


def    A (      lowercase				)     ->						str:
		'''simple docstring'''

		if len(re.findall('[ATCG]'					, lowercase				)				) != len(lowercase				):
				raise ValueError('Invalid Strand'				)

		return dna.translate(dna.maketrans('ATCG'					, 'TAGC'				)				)


if __name__ == "__main__":
					import doctest

					doctest.testmod()
