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
noe = input()
k   = input()
ar  = []
while noe:
    noe-=1
    ar.append(input())
ar.sort()

min_diff = 1000000000
for i in xrange(len(ar) - k +1):
    min_diff = min(min_diff, ar[i+k-1] - ar[i])
print min_diff