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()
lsp = itertools.combinations_with_replacement(range(K),N)
ans = 0
for p in lsp:
    lsg2 = [[] for i in range(K)]
    for i in range(N):
        lsg2[p[i]].append(lsn[i])
    maxa = 0
    mina = 10000
    f = True
    for i in range(K):
        if len(lsg2[i]) == 0:
            f= False
            break
        maxa = max(maxa,sum(lsg2[i])/len(lsg2[i]))
        mina = min(mina,sum(lsg2[i])/len(lsg2[i]))
    if f:
        ans = max(ans,math.ceil(maxa-mina))
print(ans)