## Bob's Function

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Points: 17 (partial)
Time limit: 2.0s
Memory limit: 512M

Problem types

Bob has a function , which is defined as follows

where , are constants.

Bob has pairs of and (). Bob wants to find some constants and so that he can maximize . Can you help him find out the max possible sum?

#### Input Specification

The first line of input contains one integer , (), the number of pairs and .

Each of the following lines contains two integers and , ().

#### Output Specification

Output one integer, the maximum .

#### Constraints

For all test cases, .

and
and
and

#### Sample Input 1

1
50 0

#### Sample Output 1

50

#### Explanation

One possible pair of and is .

#### Sample Input 2

5
80 20
60 50
40 40
15 10
70 30

#### Sample Output 2

220

#### Explanation

One possible pair of and is .

• For , , since , , which is
• For , , since , , which is
• For , , since and , , which is
• For , , since and ,
• For , , since , , which is

Thus, the total sum is . It's the maximum possible sum.