A "Magic Polygon" is a regular polygon (a polygon with all equal side lenghts) with n sides where its area and perimeter are numerically equal. Given n, calculate the area of such a polygon.
Input
A single integer n (3 \le n \le 10^6).
Output
Print the area of the polygon, if there are multiple correct answers, you can output any of them. Your answer will be considered correct if its absolute or relative error does not exceed 10^{-6}.
Any standard notation (including scientific) is acceptable.
Examples
| standard input | standard output |
|---|
| 4
| 16
|
| 3
| 20.7846096
|