DEJAVU

문제

N points are placed in the coordinate plane. 

Write a program that calculates how many ways we can choose three points so that they form a right triangle with legs parallel to the coordinate axes. 

A right triangle has one 90-degree internal angle. The legs of a right triangle are its two shorter sides. 

입력

The first line of input contains the integer N (3 ≤ N ≤ 100000), the number of points. 

Each of the following N lines contains two integers X and Y (1 ≤ X, Y ≤ 100 000), the coordinates of one point. 

No pair of points will share the same pair of coordinates. 

출력

Output the number of triangles. 

 

3
4 2
2 1
1 3

0

5
1 2
2 1
2 2
2 3
3 2

4

6
10 10
20 10
10 20
20 20
30 20
30 30

8