




"""simple docstring"""




from math import factorial



def     a__ (				snake_case__ = 20				)						->					int:
			lowerCamelCase			      =					2 * n  # middle entry of odd rows starting at row 3 is the solution for n = 1,
			# 2, 3,...
			lowerCamelCase			      =					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:
															lowerCAmelCase							:			List[str]     							=							int(sys.argv[1])
															print(solution(n))
										except ValueError:
															print("""Invalid entry - please enter a number.""")






def 						UpperCamelCase					(lowercase_: int = 10					)     ->      str:
	if not isinstance(lowercase_    ,      lowercase_					) or n < 0:
		raise ValueError("""Invalid input"""					)
	A__							:    List[str]        =		10**n
	A__							:    Any        =		28433 * (pow(2    ,      7830457    ,      lowercase_					)) + 1
	return str(number % modulus					)


if __name__ == "__main__":
	from doctest import testmod

	testmod()
	print(f'''{solution(10) = }''')



