


from math import factorial





def 	_lowerCAmelCase       (    _lowerCAmelCase = 20 )						->	int:


						'''simple docstring'''






						__snake_case				=		2 * n  # middle entry of odd rows starting at row 3 is the solution for n = 1,
						# 2, 3,...
						__snake_case				=		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:
			A							:					int     						=     int(sys.argv[1])
			print(solution(n))
		except ValueError:
			print('Invalid entry - please enter a number.')









from __future__ import annotations

from collections.abc import Iterator






class     UpperCamelCase:


					def __init__(						self	:		Union[str, Any]     ,    SCREAMING_SNAKE_CASE	:		int						)			->	None:




											'''simple docstring'''

											__snake_case				=		value
											__snake_case				=		None
											__snake_case				=		None






class     UpperCamelCase:


					def __init__(						self	:		int     ,    SCREAMING_SNAKE_CASE	:		Node						)			->	None:




											'''simple docstring'''

											__snake_case				=		tree


					def 							SCREAMING_SNAKE_CASE_  (						self	:		List[str]     ,    SCREAMING_SNAKE_CASE	:		Node | None						)			->	int:




											'''simple docstring'''

											if node is None:
																	return 0
											return node.value + (
											    self.depth_first_search(node.left						) + self.depth_first_search(node.right						)
											)






					def __iter__(						self	:		int						)			->	Iterator[int]:




											'''simple docstring'''

											yield self.depth_first_search(self.tree						)


if __name__ == "__main__":
	import doctest

	doctest.testmod()





