Flies
One of Bach's favorite activities is training flies. Here's a trick he taught them: N flies are arranged in a circle, with each pair of neighboring flies separated by a distance of D centimeters (measured directly, not along the circle). Each fly then begins to move at the same speed towards its neighbor in a clockwise direction. At every moment, the speed of each fly is directed precisely towards its corresponding neighbor. Eventually, all the flies will converge at a single point—that's the trick. However, as programmers, we're more interested in calculating the total distance each fly will travel during this process.
Input consists of two integers: N and D (2 ≤ N ≤ 1000, 1 ≤ D ≤ 10000). The numbers are separated by spaces.
Output
The output file should contain one real number, formatted to two decimal places, representing the solution to the problem.