My kid's kindergarten class is putting up a Christmas play.  (I hope he gets the lead role.)  The kids are all excited, but the teacher has a lot of work.  She has to produce costumes for a scene with K soldiers.  She wants to buy all the costumes in the same size, allowing for some small amount of length alteration to be done by the kids' parents later.  So she has taken all the kids' height measurements.  Can you help her select K kids from her class of N to play the soldier role, such that the height difference between the tallest and shortest in the group is minimized, and alternations will be easiest?  Tell her what this minimum difference is.
 
INPUT
The first line contains the number of test cases T. T test cases follow each containing 2 lines.
 
The first line of each test case contains 2 integers N and K.
The second line contains N integers denoting the height of the N kids.
 
OUTPUT
Output T lines, each line containing the required answer for the corresponding test case.
 
CONSTRAINTS
T <= 30
1 <= K <= N <= 20000
1 <= height <= 1000000000 

SAMPLE INPUT

3
3 1
2 5 4
3 2
5 2 4
3 3
2 5 4

SAMPLE OUTPUT

0
1
3

EXPLANATION
In the first test case, the teacher needs to only select 1 kid and hence she can choose any kid since the height difference is going to be 0.
In the second test case, the teacher can choose kids with height 4 and 5.
In the third test case, the teacher is forced to choose all 3 kids and hence the answer = 5-2 = 3

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	RAJAT SINGH: 2014-03-15 20:28:46 Very easy problem got AC in second time......
	Amit garg: 2014-01-17 09:16:53 running program correctly on ideone but showing comile error here Last edit: 2014-01-17 09:17:30
	Rudradeep Mukherjee: 2013-07-12 06:14:16 Don't know what happened. Submitted the same code again and it got AC. :) Last edit: 2013-07-12 06:18:52
	Hasil Sharma: 2013-07-07 19:53:08 O(nlogn+n) !! indeed
	Rana Saha: 2013-07-04 21:45:01 cakewalk!
	Centurion: 2013-06-11 11:31:04 can anyone explain this test case and what will be the answer for it? 5 3 1 9 16 21 22
	Aswin Murugesh: 2013-05-21 15:24:36 I am getting WA but the given test cases are giving correct answers. Any tricky test cases?
	Shubham Sharma: 2013-03-14 20:59:14 very easy
	***: 2013-03-07 17:02:36 plzz give some more test cases
	Secret: 2012-08-21 11:59:33 my code is accepted in O(nlogn+n).no need to I/O optimization ...