HASANCIRCLE - Goni the Geometrician

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Recently, Goni read a book by Plato. Inspired by Plato's life, he decided to invent a theorem related to geometry. While attempting to prove his own theorem, he encountered a problem and needs help to solve it.





Here the center of this circle is O(0,0).  OA lies on X axis. And CB || OA . You have to find the area of ABCO.

INPUT: The first line contains two integers  x,y, denoted the coordinate of C(x,y).

The next line contain one integer r .denoted the radius of this circle.

OUTPUT : Print  the area of ABCO . The value calculated must be presented with 3 digits after the decimal point.

Sample input:

1 1

2

Sample output:

1.047


Sample input:

3 8

25

 

Sample output:


101.790

 



Added by:Ruhul
Date:2019-08-04
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All