Contest Duration: - (local time) (100 minutes) Back to Home
C - Maximum Volume /

Time Limit: 2 sec / Memory Limit: 1024 MB

• 1 ≤ L ≤ 1000
• L は整数

入力

L


入力例 1

3


出力例 1

1.000000000000


入力例 2

999


出力例 2

36926037.000000000000


Score : 300 points

Problem Statement

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}.

Sample Input 1

3


Sample Output 1

1.000000000000


For example, a rectangular cuboid whose dimensions are 0.8, 1, and 1.2 has a volume of 0.96.

On the other hand, if the dimensions are 1, 1, and 1, the volume of the rectangular cuboid is 1, which is greater.

Sample Input 2

999


Sample Output 2

36926037.000000000000