One day Rabbit went to check his carrot’s field. But it was unpleasantly surprised when discovered that some part of the carrot bushes was crushed to the ground with unseen force. After a detailed scrutiny of the field Rabbit noticed that all trampled carrots form a pattern, which is based on an equilateral triangle with side \textit{\textbf{L}}. In the plane of this triangle there is a point \textit{\textbf{S}}. The projections of this point on the sides of triangle divide each side into two parts. At each sides and its parts are build semicircles as at diameters, which consist of three figures in the form of drops. \includegraphics{https://static.e-olymp.com/content/91/91ef85d38c754fdcf99642f795e9d8245f1e0f49.jpg} Rabbit was curious about what area of plantations damaged by the unprecedented power, but, unfortunately, this task was not under force for him. Your task is to help Rabbit. \InputFile In the single line is given an integer \textbf{L} (\textbf{0} < \textbf{L} ≤ \textbf{10^6}). \OutputFile Put out one number with an accuracy of \textbf{3} decimal places - the total area of damaged planting’s field of Rabbit.