Big Keng

It is a non-cover container, the upper part of it is a cylindrical surface which radius is R and hight is H, the lower part of it is a round table of upper radius R and under radius r, height h, r < R.
If the volume is given, find the value of minimum surface area.

cylinder
round table
Input

There are multiple cases. Each case is only one line containing the given volume.

Output

Each output contains one floating number indicationt the minimum surface area. Round to six digits behind the decimal point.
Please note that we didn't provide full output in the sample output area below, you should output at least six digits after the decimal point.

Sample Input

1
2
Sample Output

3.9...
6.2...

http://www.cnblogs.com/xiezie/p/5501901.html

http://www.lxway.com/506985912.htm