COCI 2007/2008, Contest #2

Task 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 ≤ 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.

Output

Output the number of right triangles.

Examples

3
4 2
2 1
1 3

1

4
5 0
2 6
8 6
5 7

0

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

7

All Submissions
Best Solutions

Point Value: 20 (partial)
Time Limit: 4.00s
Memory Limit: 32M
Added: Nov 13, 2010

Languages Allowed:
C++03, PAS, C, HASK, ASM, RUBY, PYTH2, JAVA, PHP, SCM, CAML, PERL, C#, C++11, PYTH3

Comments (Search)

I put this problem up in a hurry because I was trying to solve it on a different online judge and I was debugging it here (yay for abuse of privileges). The typo is fixed.