Maximum Volume

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

inputFormat

Input

Input is given from Standard Input in the following format:

L

outputFormat

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

样例

999

36926037.000000000000