You arrive m Ye Olde Magic Shoppe with some hard-earned gold to purchase wondrous and
unique magic items. There are n such items in the shop, each of them locked in a special magic
box. The i-th box costs ci gold pieces to buy, and contains an item worth vi gold pieces. The
costs and item values are known to you, as you have previously read, mastered, and memorized
Ye Olde Magic Catalogue.
A mortal, such as you, can safely carry only one magic item. You therefore aim to get the
most precious one. And obtain it you would, if not for a malicious, magical creature, known as
The Imp can cast a mischievous spell, which transforms the content of any magic box into
worthless dust. Of course, he will use the spell just after you buy a box, to make you pay for the
item and not get it. You are thus forced to buy another box, and then the next one_
The Imp has enough magic to cast the spell at most k times. He can, of course, refrain from
using it, allowing you to keep an item. You can walk away at any time, empty-handed (though
it would surely be a disgrace). However, if you get an item, you must keep it and leave the shop.
You aim to maximize your gain (the value of the acquired item minus all the expenses paid
previously), while The Imp wants to mimmize it. If both vou and the creature use the optimal
strategy, how much gold will vou earn?
The first line of input contains the number of test cases T. The descriptions of the test cases
Each test case starts with a line containing the number of items n (1《n≤ 150 000) and the
the maximum number of The Imp's spells k (0≤ k < 9). The next n lines contain the items'
values and costs, the i-th line containing the numbers vi and ci, in that order (0≤ vi, ci≤ 10^6).
For each test case, output one line containing your gain