Problem C. Count Squares ≡

Author:	B. Vasilyev, A. Klenin		Time limit:	3 sec
Input file:	input.txt		Memory limit:	64 Mb
Output file:	output.txt

Statement

Given a set of points with integer coordinates x_i, y_i, i = 1… N, your program must find all the squares having each of four vertices in one of these points.

Input file format

Input file contains integer N followed by N pairs of integers x_i y_i.

Output file format

Output file must contain a single integer — number of squares found.

Constraints

−10⁴ ≤ x_i, y_i ≤ 10⁴, 1 ≤ N ≤ 2000. All points in the input are different.

Sample tests

No.	Input file (input.txt)	Output file (output.txt)
1	4 0 0 4 3 -3 4 1 7 copy	1 copy
2	9 1 1 1 2 1 3 2 1 2 2 2 3 3 1 3 2 3 3 copy	6 copy

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