

'''simple docstring'''







def  UpperCAmelCase__      ( UpperCAmelCase__ = 10_00			)     ->     int:
       return sum(2 * a * ((a - 1) // 2) for a in range(3,    n + 1			)			)


if __name__ == "__main__":
      print(solution())



'''simple docstring'''







from functools import lru_cache
@lru_cache
def  UpperCAmelCase__      ( UpperCAmelCase__			)     ->     int:
       if num < 0:
              raise ValueError("""Number should not be negative."""			)

       return 1 if num in (0, 1) else num * factorial(num - 1			)


if __name__ == "__main__":
      import doctest

      doctest.testmod()
