13:I[87,["736","static/chunks/89fc4f0e-9e200ae6a0166583.js","401","static/chunks/363642f4-32903b9154b7835a.js","153","static/chunks/153-58eddeb032cc4608.js","131","static/chunks/131-05ce00cfd760e12b.js","87","static/chunks/87-b76b60eef573119a.js","286","static/chunks/app/problem/%5Bid%5D/page-45cf3875257fc32e.js"],"Header"] 14:I[1742,["736","static/chunks/89fc4f0e-9e200ae6a0166583.js","401","static/chunks/363642f4-32903b9154b7835a.js","153","static/chunks/153-58eddeb032cc4608.js","131","static/chunks/131-05ce00cfd760e12b.js","87","static/chunks/87-b76b60eef573119a.js","286","static/chunks/app/problem/%5Bid%5D/page-45cf3875257fc32e.js"],"ProblemView"] 15:T5d5,

You are given n points on a plane. All the points are distinct, and no three of them lie on the same line. Find the number of parallelograms with vertices at the given points.

Input

The first line of the input contains an integer n (1 ≤ n ≤ 2000) — the number of points.

Each of the next n lines contains two integers (x_i, y_i) (0 ≤ x_i, y_i ≤ 10⁹) — the coordinates of the i-th point.

Output

Print the only integer

Number of Parallelograms

Examples