





'''simple docstring'''


from math import factorial


def 						__a(SCREAMING_SNAKE_CASE_	:       int = 20     ):



    '''simple docstring'''





    _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(SCREAMING_SNAKE_CASE_     ) / (factorial(SCREAMING_SNAKE_CASE_     ) * factorial(n - k     ))     )


if __name__ == "__main__":
       import sys

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



'''simple docstring'''

from __future__ import annotations



def snake_case_      (					__snake_case  :							list[int | str])			->					None:
   create_state_space_tree(__snake_case	,   []	,   0	,   [0 for i in range(len(__snake_case))])



def snake_case_      (					__snake_case  :							list[int | str]	,   __snake_case  :							list[int | str]	,   __snake_case  :							int	,   __snake_case  :							list[int]	,   )			->					None:

   if index == len(__snake_case):
      print(__snake_case)
      return

   for i in range(len(__snake_case)):
      if not index_used[i]:
         current_sequence.append(sequence[i])
         lowerCAmelCase_			=      True
         create_state_space_tree(__snake_case	,   __snake_case	,   index + 1	,   __snake_case)
         current_sequence.pop()
         lowerCAmelCase_			=      False
A_     :						list[int | str]    							=[3, 1, 2, 4]
generate_all_permutations(sequence)

A_     :						list[int | str]    							=["A", "B", "C"]






generate_all_permutations(sequence_a)





