King Brian is looking at rectangles!

He has a list of points and can select any four at random. If the four points form the four corners of an **axis aligned** rectangle, he writes down the area.

What is the largest possible area he can get from selecting four random points?

**Note: axis aligned means that the four lines that form the rectangle are all either horizontal or vertical (aligning with the and axes respectively).**

#### Constraints

For all subtasks:

No two points will be the same.

##### Subtask 1 [15%]

##### Subtask 2 [70%]

##### Subtask 3 [15%]

No additional constraints.

#### Input Specification

The first line will contain the integer .

The next lines will each contain two space separated integers: , .

#### Output Specification

Output one line, the maximum possible area of an **axis aligned** rectangle King Brian can get from selecting four random points. If no rectangles can be formed, print .

#### Sample Input

```
9
1 1
5 5
7 7
5 7
7 5
10 10
5 10
10 5
20 20
```

#### Sample Output

`25`

#### Sample Explanation

There are two possible rectangles that can be constructed with the points:

- From to with an area of
- From to with an area of

Thus the answer is .

## Comments

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nice absolute value around xi and yi