MIT Individual Contest 2007

You are given a set S of N points in the plane and must count the number of distinct axis-parallel rectangles whose four vertices all lie in S (that is, count those rectangles which have two sides parallel to the x-axis, and the other two sides parallel to the y-axis).

Input

The first line of the input is N (1 ≤ N ≤ 250000), the number of points in S. N lines then follow, where the i-th line is of the form "x_i y_i", giving the coordinates of a point (x_i, y_i) in S. All given points are distinct, and all coordinates fit into a 32-bit signed integer.

Output

Your output should consist of a single number, the number of distinct axis-parallel rectangles whose four vertices all lie in S, followed by a newline.

Example

Input:
6
-1 0
-1 1
0 0
0 1
1 0
1 1

Output:
3