### Problem Statement

You are given a int **length** . We have a regular hexagon: a polygon with six sides, in which all internal angles have 120 degrees and **length** is the length of each side. We are going to draw three non-intersecting diagonals in some way. These will divide the hexagon into four triangles. We will then compute their areas, take a piece of paper and write down the *smallest* of those four areas. Compute and return the *largest* number we can obtain on our piece of paper (by choosing which diagonals to draw).

Examples

5

Returns: 10.825317547305485

10

Returns: 43.30127018922194

100000

Returns: 4.330127018922194E9