import itertools
import sys
import copy
import math
N = int(input())
K = int(input())
lsn = [int(input()) for i in range(N)]
if N==K:
    print(max(lsn)-min(lsn))
    sys.exit()
group = [[lsn[i]] for i in range(K)]
lsk = lsn[K:]
lsp = itertools.product(range(K),repeat=N-K)
ans = 0
for p in lsp:
    lsg2 = copy.deepcopy(group)
    for i in range(N-K):
        lsg2[p[i]].append(lsk[i])
    maxa = 0
    mina = 10000
    for i in range(K):
        maxa = max(maxa,sum(lsg2[i])/len(lsg2[i]))
        mina = min(mina,sum(lsg2[i])/len(lsg2[i]))
    ans = max(ans,math.ceil(maxa-mina))
print(ans)