N = int(input())
K = int(input())
n = [int(input()) for i in range(N)]

ans = 0
for bit in range(3 ** 9):
    grp = [0] * 3
    grplen = [0] * 3
    for i in range(N):
        j = (bit // (3 ** i)) % 3
        grp[j] += n[i]
        grplen[j] += 1
    if min(grplen) == 0:
        continue
    otherlen = [1] * N
    lenprod = 1
    for i in range(3):
        lenprod *= grplen[i]
        for j in range(3):
            if i == j:
                continue
            otherlen[i] *= grplen[j]
    if lenprod == 0:
        continue
    for i in range(3):
        grp[i] *= otherlen[i]
    ans = max(ans, (max(grp) - min(grp) + lenprod - 1) // lenprod)
print(ans)