Hares and Polygons. EASY#3266
rabbits are positioned at the vertices of a regular -gon with side length . They all start moving simultaneously at a constant speed . The first rabbit always moves towards the second rabbit, the second towards the third, the third towards the fourth, and so on, with the -th rabbit moving towards the first. After a certain time , all rabbits will converge at a single point. Your task is to help them determine how long they need to run to meet.
Each test case provides numbers: an integer (1 \le N \le 10^3), a real number (0 < a \le 10^6), and a real number (0 \le v \le 10^6).
Output the minimum time required for the rabbits to meet, formatted to decimal places. If the rabbits will never meet, output .
Example 1