D. Bucket of sand
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

A thin stream of sand is poured into a conical fire bucket with a height of $$$ h $$$ and an upper diameter of $$$ d $$$. The sand is poured strictly into the center of the bucket, installed vertically, and forms a pile. As soon as the top of the pile reaches the upper edge of the bucket, the process stops. Find the volume of sand poured into a bucket if it is known that the angle at the base of a pile of sand poured onto a flat surface is 34 degrees.

Input

A single line contains two integers $$$ h $$$ ($$$ 1 \leq h \leq 1000 $$$) and $$$ d $$$ ($$$ 1 \leq d \leq h $$$), separated by a space.

Output

Print a singular number – the volume of sand poured into the bucket, specified with an accuracy of $$$ 10^{-6} $$$.

Examples
Input
10 10
Output
146.39985672107267
Input
5 1
Output
1.1487958374076184
Note

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