Grammy loves geometry. Today, she takes out her precious convex polygon and plays with it.

Grammy thinks that symmetry is a fun characteristic for a convex polygon, so she draws out all the axes of symmetry on the polygon.

NIO is a naughty boy. He repeats the following operation several times. In each operation, he chooses an axis of symmetry as the rotation axis and rotates the polygon along the axis arbitrarily. Note that after rotating the polygon, the axes of symmetry will also rotate with the polygon.

Grammy wants to know the total volume that can be sweeped by the convex polygon during NIO's operations. Please help her.

The first line contains an integer  (), denoting the number of vertices of the convex polygon. 

In each of the next  lines contains two integers  (), denoting the coordinates of the -th vertex. The vertices are given in counterclockwise order. 

It is guaranteed that the polygon does not self-intersect at any point.

Output a real number, denoting the volume of the sweeped area. Your answer will be considered correct if the absolute or relative error is less than .

3
0 -1
1 0
0 1

1.047197551197

3
1 1
4 5
1 4

0