
from math import factorial
def 							SCREAMING_SNAKE_CASE_	(					UpperCAmelCase_	:     int = 2_0				)			->						int:
       SCREAMING_SNAKE_CASE_							:				Tuple		=2 * n  # middle entry of odd rows starting at row 3 is the solution for n = 1,
       # 2, 3,...
       SCREAMING_SNAKE_CASE_							:				Optional[int]		=n // 2

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


if __name__ == "__main__":
 import sys

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


def 							SCREAMING_SNAKE_CASE_	(					UpperCAmelCase_	:     int = 1_0_0_0				)			->						int:
       SCREAMING_SNAKE_CASE_							:				int		=2**power
       SCREAMING_SNAKE_CASE_							:				Tuple		=0
       while n:
              SCREAMING_SNAKE_CASE_	,     SCREAMING_SNAKE_CASE_							:				Union[str, Any]		=r + n % 1_0, n // 1_0
       return r


if __name__ == "__main__":
 print(solution(int(str(input()).strip())))
