Migrated from Lutece 2835 Carving

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Description

Little Rabbit is good at carving. Now he wants to get a wooden sphere, but he only has a wooden triangular pyramid. So he decides to carve it into a sphere.

The following picture shows the triangular pyramid that Little Rabbit has. The edges $AD, BD, CD$ are vertical with each other.

It's not hard for Little Rabbit to carve it, but he wants to know what's the maximum volume of the sphere he can get.

Input

The input contains three integers $a,b,c\ (1 \le a,b,c \le 1000)$, indicating the lengths of edges $AD,BD,CD$ respectively.

Output

Output the maximum volume of the sphere Little Rabbit can get. The answer should be rounded to $2$ decimal places.

Samples

1 2 3

0.16

Resources

The 18th UESTC Programming Contest Preliminary