import itertools,math
N = int(raw_input())
K = int(raw_input())
n = [int(raw_input()) for _ in xrange(N)]
ans = 0
for group in itertools.product(xrange(K),repeat=N):
    if not all(group.count(i) for i in xrange(K)): continue
    ave = [0.0]*K
    for i in xrange(N): ave[group[i]] += n[i]
    for i in xrange(K): ave[i] /= group.count(i)
    ans = max(ans,int(math.ceil(max(ave)-min(ave))))
print ans