# The Cheese for Anfisa

# 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 ^{ o}** 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.

2 3 90

8.485