Pocky is a popular chocolate bar. And also to make an unlucky butler to get one hardly ... But we can get a lot to eat easily. Apart from the taste, the boring student \textbf{L} likes to take out one by one to make a regular polygon. And after that, he would like to know the area of the regular polygon. \includegraphics{https://static.e-olymp.com/content/b5/b5494814a3db05c6311916f8c5210941365c758c.jpg} \InputFile One line for each case, only one positive integer \textbf{N} (\textbf{N} ≤ \textbf{32768}). Indicate the number of the regular polygon's edges. And the length of every regular polygon's edge is \textbf{1} permanently. The case \textbf{N} < \textbf{3}, indicate the end of input, and no output for it. \OutputFile A real number for each case, indicate the area of the regular polygon. Retained two digits after the decimal point.