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# Pravokutni

$N$ 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.

## Input

The first line of input contains an integer $N$ ($3 \le N \le 1500$), 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 $-10^9$ and $10^9$.

No two points will be located at the same coordinates.

## Output

Output the number of right triangles.

Sample Input 1 Sample Output 1
3
4 2
2 1
1 3

1

Sample Input 2 Sample Output 2
4
5 0
2 6
8 6
5 7

0

Sample Input 3 Sample Output 3
5
-1 1
-1 0
0 0
1 0
1 1

7

CPU Time limit 2 seconds
Memory limit 1024 MB
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