You have n bottles that can be considered as cylinders of a unit radius. At first you want to draw a circle and place all your bottles inside it so that each of the bottle bottoms touches the circle. What is the minimum radius of such circle?

Input

The only line contains an integer n that is the number of bottles (1 ≤ n ≤ 10).

Output

Output the minimum radius of a circle with precision 10⁻⁶.

Samples