you are given an array of size N. You need to select K elements from the array such that the difference between the max number among selected and the min number among selected array elements should be minimum. Print the minimum difference.

INPUT:
First line N number i.e., length of array
Second line K number 
Next N lines contains a number for each line

OUTPUT:
Print the minimum possible difference

0<N<10^5
0<K<N
0<number<10^9

SAMPLE INPUT
5
3
1
2
3
4
5

SAMPLE OUTPUT
2
# your code goes here
"""created by : rjohari23"""

n = int(raw_input())
k = int(raw_input())
a = []
for _ in range(n):
	num = int(raw_input())
	a.append(num)

a.sort()
maxi = 1000000000
for i in range(n-k+1):
	temp = a[i+k-1] - a[i]
	if temp<maxi:
		maxi = temp
	
print maxi