Maximum Fenced Area

Given a total length \(l\) of available fencing material, your task is to compute the maximum area of a rectangular field that can be enclosed when one side of the field is provided naturally (for example, by a river). In this problem, you only need to fence three sides of the rectangle.

Mathematically, if the total fencing length is \(l\), then the optimal area \(A\) is given by:

\(A = \frac{l^2}{8}\)

Print the computed area as a floating point number with six decimal places.

inputFormat

The input consists of a single integer \(l\) (\(1 \le l \le 10^9\)) representing the total length of available fencing material. The input is provided via standard input.

outputFormat

Output the maximum fenced area as a floating point number computed by the formula \(\frac{l^2}{8}\). The result must be printed with exactly six decimal places. Output the answer to standard output.

100

1250.000000