Pocky#3794
Pocky is a popular chocolate bar. It is hard for an unlucky butler to get one... But we can easily get a lot to eat.
Apart from the taste, the boring student likes to take them out one by one to make a regular polygon.
And after that, he would like to know the area of the regular polygon.
One line for each case, only one positive integer (N \le 32768). The number denoting the sides of the regular polygon. The length of every regular polygon's side is always .
The case N < 3, indicate the end of input, and no output for it.
For each case, output a real number representing the area of the regular polygon, rounded to two decimal places.
Beispiel 1