problem

Given the lengths of $ 2 $ sides that are not the hypotenuse of a right triangle, $ A $ and $ B $. The side of length $ A $ overlaps the $ x $ axis, and the side of length $ B $ overlaps the $ y $ axis.

Do the following:

1. Rotate the triangle around the $ x $ axis.
2. Rotate the shape created by performing the operation $ 1 $ around the $ y $ axis.

Perform the operation $ 2 $ to find the volume of the created figure.

output

Output the volume of the figure. Also, output a line break at the end. Absolute or relative errors less than $ 0.000001 $ are allowed.

Example

Input

1 2

Output

33.510322

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