Pie Are Squared

Given the radius of a circle, calculate and print its area.

The area of a circle can be computed using the following formula:

For pi, you can use 3.141592653589793, or acos(-1).

Input

The input will contain one floating-point number $r$ ($0 < r < 2000$).

Output

Print the area of the circle (accurate to $10^{-4}$).

Sample

2

12.5663706144