SP21170 TAP2014C - Constellation of the parallelogram

**\[The original version of this problem (in Spanish) can be found at [http://dc.uba.ar/events/icpc/download/problems/tap2014-problems.pdf](http://dc.uba.ar/events/icpc/download/problems/tap2014-problems.pdf "http://dc.uba.ar/events/icpc/download/problems/tap2014-problems.pdf") \]** One morning, when Cyrus Samsa woke from troubled dreams, he found himself lying on his bed, but not transformed into a monstrous insect. However, when he looked at the still starry sky, he found that the visual setting of cosmos showed four stars positioned as the vertices of a perfect parallelogram. Being a big geometry enthusiast, he called those four stars "constellation of the parallelogram".

The first line contains an integer **N** indicating the number of stars on the image to be analyzed (**4 ****1000**).**** The following **N** lines describe each of the stars on the image with two integers **X $ _{i} $** and **Y $ _{i} $** , indicating respectively the **X** and **Y** coordinates of the star on the Cartesian plane (**-10 $ ^{8} $** ****X $ _{i} $ , Y $ _{i} $** ****10 $ ^{8} $** for **i = 1, 2, ..., N**). You may assume that no two stars on the image are on the same position.****

Print a single line containing a single integer representing the number of sets of four points on the input image that are the vertices of a parallelogram.