


from math import factorial






def 							__lowercase   ( __lowerCAmelCase							:				int = 2_0   ):
							a__             =     2 * n  # middle entry of odd rows starting at row 3 is the solution for n = 1,
							# 2, 3,...
							a__             =     n // 2

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


if __name__ == "__main__":
						import sys

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











'''simple docstring'''







def  _lowerCamelCase				( lowercase						:      bytes						)	->	str:
				return "".join([hex(lowercase						)[2:].zfill(2						).upper() for byte in list(lowercase						)]						)






def  _lowerCamelCase				( lowercase						:      str						)	->	bytes:
				# Check data validity, following RFC3548
				# https://www.ietf.org/rfc/rfc3548.txt
				if (len(lowercase						) % 2) != 0:
								raise ValueError(
								    "Base16 encoded data is invalid:\nData does not have an even number of hex digits."						)
				# Check the character set - the standard base16 alphabet
				# is uppercase according to RFC3548 section 6
				if not set(lowercase						) <= set("0123456789ABCDEF"						):
								raise ValueError(
								    "Base16 encoded data is invalid:\nData is not uppercase hex or it contains invalid characters."						)
				# For every two hexadecimal digits (= a byte), turn it into an integer.
				# Then, string the result together into bytes, and return it.
				return bytes(int(data[i] + data[i + 1]    ,							16						) for i in range(0    ,							len(lowercase						)    ,							2						)						)


if __name__ == "__main__":
					import doctest

					doctest.testmod()
