\problemname{Basalt Breakdown}
\illustration{0.34}{svartifoss.jpg}{\href{https://publicdomainpictures.net/en/view-image.php?image=49441}{Svartifoss} by Piotr Wojtkowski, CC0 Public Domain\vspace{-3mm}}%
One of Iceland's most popular attractions is \emph{Svartifoss} (``black
waterfall''). Its name derives from the black hexagonal basalt columns that
frame the waterfall on either side. Originally formed from cooling lava,
centuries of erosion have shaped the columns into their characteristic shape.

A group of geologists at RU went on an excursion to Svartifoss. They took some
probes and performed various measurements on the hexagonal rocks that have
broken off the basalt walls.

Just as they return to RU, they realise that they have forgotten a crucial
measurement. They have determined the area of the hexagonal face, but they did
not write down what its perimeter was. Assuming that the face has the shape of
a perfect regular hexagon, help the geologists compute the perimeter.

\section*{Input}

The input consists of:
\begin{itemize}
  \item One line with an integer $a$ ($1 \le a \le 10^{18}$), the area of the
    hexagonal rock face in square centimetres.
\end{itemize}

\section*{Output}

Output the perimeter of the rock face in centimetres. Your answer should have an
absolute or relative error of at most $10^{-6}$.
