Contests | Virtual Contests | Problems | Submit | Runs Status | Rank List | Forum |

Time Limit: 1.0 Seconds Memory Limit: 65536K

Total Runs: 243 Accepted Runs: 90

Given is
*n* points with integer coordinates in the plane. Is it 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.
### Sample input

### Output for sample input

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 ≤ *n* ≤ 100000 giving the
number of points for this test case. It is followed by *n* pairs of
integers specifying the *x* and *y* coordinates of the points for
this case.

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`.

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

12

Maintance:G.D.Retop. Developer: SuperHacker, G.D.Retop