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