프로그램 명: coci_dejabu
제한시간: 1 초

[문제요약] 좌표 상에 N 개의 점이 있다.

직각을 끼고 있는 두 변이 축에 평행하는 직각 삼각형의 개수를 구하는 것이다.

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.

입출력 예

input 

3 
4 2 
2 1 
1 3 

output 

0 

input 

5 
1 2 
2 1 
2 2 
2 3 
3 2 

output 

4 

input 

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

output 

8

출처:coci 2007-2008 contest3 4/6
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