## Description:

John likes playing Warcraft III. Now, he is teaching his girlfriend to play it. In Warcraft III, there are many kinds of units. Every unit costs some gold and lumber. Different units have different attack value.

Now question comes. Given some amount of gold and a list of types of units, how to arrange your units to maximize the attack value of your units. Assume you have infinite lumbers.

## Input:

Line 1 contains an integer T: the number of test cases.

Next T blocks, each starts with two integers: G and U, represents the amount of gold and number of unit type. Next U lines, each contains two integers: attack value of a type of unit and the cost.

## Output:

For each test case, output the maximum total attack value in one line.

## Sample Input:

2

100 1

20 10

300 4

100 60

250 120

120 100

35 20

## Sample Output:

200

605

## Note:

本题由旧版NOJ导入，来源：NUPT ACM 2010 Personal Ranking Contest