0052

The Cheese for Anfisa ⬀

The master was making dinner for Anfisa which symbolize 2008 year. He used a special knife which cuts up the cheese on the identical rectangular parallelepipeds with basis like square with the side of A and the high B.

But Anfisa liked to use cheese with size less then master did as well as becomes to the lady of year. Anfisa always establishes the cheese strictly vertical and by a square to the table and cuts the offered piece of sweets on two parts. When Anfisa cuts the pieces of cheese the knife always took a place on a diagonal of the square. But Anfisa not always can cut a piece in a half because the plane of blade of the knife formed the dihedral angle of Z° with the plane of basis.

You have find the area S of the figure which formed by Anfisa when she cuts the piece.

Input

Three integers A, B, Z, no more than 90.

Output

The area S of the figure formed by Anfisa when she cuts the piece; print the area with 3 digits after the decimal point.

Time limit 1 second

Memory limit 64 MiB

Input example

2 3 90

Output example

8.485