문제

N points are placed in the coordinate plane. Write a program which calculates in how many ways a right triangle can be formed by three of the given points. A right triangle is one in which one of the angles is 90 degrees.

입력

The first line of input contains an integer N (3 ≤ N ≤ 1500), the number of points. Each of the following N lines contains the coordinates of one point, two integers separated by a space. The coordinates will be between −109 and 109. No two points will be located at the same coordinates.

출력

Output the number of right triangles.

예제 입력 1

3
4 2
2 1
1 3

예제 출력 1

1

예제 입력 2

4
5 0
2 6
8 6
5 7

예제 출력 2

0

예제 입력 3

5
-1 1
-1 0
0 0
1 0
1 1

예제 출력 3

7