




from math import factorial





def        __UpperCAmelCase						(							lowerCamelCase_ :     int = 20  )       ->  int:







			"""simple docstring"""





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








a_      :      str    =     6_55_21






def     __a					(		__UpperCAmelCase       ):
 a__												= 1
 a__												= 0
 for plain_chr in plain_text:
  a__												= (a + ord(__UpperCAmelCase       )) % MOD_ADLER
  a__												= (b + a) % MOD_ADLER
 return (b << 16) | a





