The first line of the input file contains an integer

The next

*n*,1<=N<=100 000.The next

*n*lines contain two integers each, the coordinates of the given points. The coordinates don't exceed 10^{9}by absolute value.内存限制：128 MiB 时间限制：5 Sec

Consider

Two points from that set are said to be

How many pairs of friends are there among the given points?

求这样的点对个数：以两点连线为对角线的矩形内不存在其他点（也不能在边界上）

The first line of the input file contains an integer *n*,1<=N<=100 000.

The next*n* lines contain two integers each, the coordinates of the given points. The coordinates don't exceed 10^{9} by absolute value.

The next

Output one integer number — the sought number of pairs of friends.

```
5
```

0 0

0 2

2 0

2 2

1 1

```
8
```