Goat in the garden#2719
A goat is tied to a stake placed exactly at the center of a square garden. The goat eats all the grass it can reach without leaving the garden or breaking the rope. Find the area of the garden that the goat will eat.
The length of a side of the garden and the length of the rope in meters are given (positive integers not exceeding , separated by space in a single line).
Print the area (in square meters, with an accuracy of decimal places) that will be eaten by the goat.
Example 1