You are given n points on a plane. All points are different.

Find the number of different groups of three points (A,B,C) such that point B is the middle of segment AC.

The groups of three points are considered unordered, that is, if point B is the middle of segment AC, then groups (A,B,C) and (C,B,A) are considered the same.

The first line contains a single integer n (3 \le n \le 3000) - the number of points.

Next n lines contain the points. The i-th line contains coordinates of the i-th point: two space-separated integers xi,yi (-1000 \le xi,yi \le 1000).

It is guaranteed that all given points are different.

Print the single number - the answer to the problem.