6744번 - Parallelogram Counting 다국어

There are n distinct points in the plane, given by their integer coordinates. Find the number of parallelograms whose vertices lie on these points. In other words, find the number of 4-element subsets of these points that can be written as {A, B, C, D} such that AB || CD, and BC || AD. No four points are in a straight line. 

The first line of the input file contains a single integer t (1 ≤ t ≤ 10), the number of test cases. It is followed by the input data for each test case.
The first line of each test case contains an integer n (1 ≤ n ≤ 1000). Each of the next n lines, contains 2 space-separated integers x and y (the coordinates of a point) with magnitude (absolute value) of no more than 1000000000.

• Output should contain t lines.
• Line i contains an integer showing the number of the parallelograms as described above for test case i.