## 0767. Cylinder

###### Time limit : 1000 ms Memory limit : 64 mb

Using a sheet of paper and scissors, you can cut out two faces to form a cylinder in the following way:

1.     Cut the paper horizontally (parallel to the shorter side) to get two rectangular parts.

2.     From the first part, cut out a circle of maximum radius. The circle will form the bottom of the cylinder.

3.     Roll the second part up in such a way that it has a perimeter of equal length with the circle's circumference, and attach one end of the roll to the circle. Note that the roll may have some overlapping parts in order to get the required length of the perimeter.

Given the dimensions of the sheet of paper, can you calculate the biggest possible volume of a cylinder which can be constructed using the procedure described above?

### Output

Print one number −the biggest possible volume of the cylinder. Round this number to 3 places after the decimal point.

Samples

 № Input Output 1 10 10 54.247 2 10 50 785.398 3 10 30 412.095