## Description

The art galleries of the new and very futuristic building of the Center for Balkan Cooperation have the form of polygons (not necessarily convex). When a big exhibition is organized, watching over all of the pictures is a big security concern. Your task is that for a given gallery to write a program which finds the surface of the area of the floor, from which each point on the walls of the gallery is visible. On the figure $1$. a map of a gallery is given in some co-ordinate system. The area wanted is shaded on the figure $2$.

## Input

The number of tasks T that your program have to solve will be on the first row of the input file. Input data for each task start with an integer $N$, $5 \leq N \leq 1500$. Each of the next $N$ rows of the input will contain the co-ordinates of a vertex of the polygon ? two integers that fit in $16$-bit integer type, separated by a single space. Following the row with the co-ordinates of the last vertex for the task comes the line with the number of vertices for the next test and so on.

## Output

For each test you must write on one line the required surface - a number with exactly two digits after the decimal point (the number should be rounded to the second digit after the decimal point).