






'''simple docstring'''






from math import factorial




def        _SCREAMING_SNAKE_CASE  (				A  :       int = 20  )    -> int:







   """simple docstring"""
   __snake_case				:      Union[str, Any]     							= 2 * n  # middle entry of odd rows starting at row 3 is the solution for n = 1,
   # 2, 3,...
   __snake_case				:      Tuple     							= n // 2

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


if __name__ == "__main__":
      import sys

      if len(sys.argv) == 1:
            print(solution(2_0))
      else:
            try:
                  __A    	=   int(sys.argv[1])
                  print(solution(n))
            except ValueError:
                  print('''Invalid entry - please enter a number.''')







'''simple docstring'''






def        _SCREAMING_SNAKE_CASE  (				A  :       float  ,		A  :       list[float]  )    -> float:







   """simple docstring"""
   if discount_rate < 0:
      raise ValueError('Discount rate cannot be negative'  )
   if not cash_flows:
      raise ValueError('Cash flows list cannot be empty'  )
   __snake_case				:      List[str]     							= sum(
       cash_flow / ((1 + discount_rate) ** i) for i, cash_flow in enumerate(A  )  )
   return round(A  ,		ndigits=2  )


if __name__ == "__main__":
      import doctest

      doctest.testmod()