Thick Coin#1318
In the city, people loved the coin game so much that two outcomes (heads, tails) were not enough for them. Therefore, they decided to construct a thick coin, one of whose possible outcomes is to land on its edge.
What is the minimum thickness required for a coin of radius so that the probability of landing on its edge is \dfrac{1}{n}? Assume the coin has the form of a right circular cylinder, and the surface onto which it is thrown is sticky (when the coin touches the surface, it lands either on its edge or on one of its bases).
Each line is a separate test and contains two integers: the radius of the coin (0 < r < 100000) and the value (1 < n < 100).
For each test, print in a separate line the minimum thickness of the coin. Print the result with digits after the decimal point.
Example 1