25279번 - Treehouse 서브태스크다국어

문제

Pusheen wants to build a treehouse in the Treehouse forest in Brunnshög in the north of Lund. The treehouse should to be built on a square platform in the treetops, with a tree in each of the four corners. When Pusheen has picked a spot to built the treehouse, trees that are located between the corners will be cut down. Pusheen has a 2D map with all the (x, y)-coordinates of the trees in the forest. In how many places can they build a square treehouse?

입력

The first line has an integer 4ドル \leq N \leq 2,円 000 ,ドル the number of trees in the forest. Each of the following $N$ lines has two integers $-10,000\leq x_i, y_i \leq 10,000,ドル the x- and y-coordinates of tree $i$. All points are distinct.

출력

An integer, the number of suitable spots for a tree house.

제한

서브태스크

힌트

Illustration of the two possible treehouse locations in sample 1.