\includegraphics{https://static.e-olymp.com/content/3f/3f534239156989092b143b72af3d4926dba93a09.jpg} Given a map of the rivers of the continent. Each river is shown as a broken line, which starts at the source of the river and ends, or at the point where the river empties into another, or estuary. Lamanov tops - or turning point of the river, or tributary confluence points. We will consider the basin as a convex polygon of minimum area that contains the river and all its tributaries. \textit{Note}: According to this definition, the river basin is the same area may belong to different basins of the rivers. \textit{Example}: Displaying the continent with three rivers. The coordinates of the rivers and the basin are given in the table. Required to find the maximum area of the river basin, located on this continent. \InputFile The first line contains the number of rivers, \textbf{N}. The next line contains \textbf{N} blocks, describing a river. Each unit number \textbf{i} is: \begin{itemize} \item A single line with \textbf{k_i} - number of vertices Lamani, describing the river; \item \textbf{k_i} lines containing a pair of real numbers \textbf{x_j} and \textbf{y_j} (\textbf{1} ≤ \textbf{j} ≤ \textbf{k_i}), separated by a space - the coordinates of points describing a river. \end{itemize} \textbf{1} ≤ \textbf{N} ≤ \textbf{10}, the amount of \textbf{k_i} ≤ \textbf{1000}, \textbf{-1000} ≤ \textbf{x_j}, \textbf{y_j} ≤ \textbf{1000}. \OutputFile Derive a single number - the area of greatest river basin with two characters after the decimal point.