7841번 - Count Squares 다국어

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

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

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

• $-10^4 \le x_i, y_i \le 10^4$, $1 \le N \le 2000$.
• All points in the input are different.