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
a=[]
t,k=input(),input()
for _ in xrange(t):
	a.append(input())
a.sort()
t=[a[x+k-1]-a[x] for x in xrange(0,len(a)-k) ]
print min(t)