Problem: Given is a positive integer L. Find the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L.

Constraints

* 1 ≤ L ≤ 1000
* L is an integer.

Input

Input is given from Standard Input in the following format:


L


Output

Print the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L. Your output is considered correct if its absolute or relative error from our answer is at most 10^{-6}.

Examples

Input

3


Output

1.000000000000


Input

999


Output

36926037.000000000000

Solution (in PYTHON):

Solution:
#!/usr/bin/env python

from sys import stdin, stderr

def main():
   L = int(stdin.readline())

   L3 = L / 3.0
   res = L3 * L3 * L3
   print(res)

   return 0

if __name__ == '__main__': main()