Time Limit: 1 s
Memory Limit: 128 MB

Submission：4
AC：4
Score：99.81

Given is

points with integer coordinates in the plane. Is it is possible to construct a simple, that is non-intersecting, rectilinear polygon with the given points as vertices? In a rectilinear polygon there are at least 4 vertices and every edge is either horizontal or vertical; each vertex is an endpoint of exactly one horizontal edge and one vertical edge. There are no holes in a polygon.

The first line of input is an integer giving the number of cases that follow. The input of each case starts with an integer 4 ≤

The output should contain one line for each case on input. Each line should contain one integer number giving the length of the rectilinear polygon passing throught the given points when it exists; otherwise, it should contain `-1`.

Please Input Input Here

Please Input Output Here

input

1
8
1 2
1 0
2 1
2 2
3 2
3 1
4 0
4 2

output

12