x = [int(i) for i in input().split()]
y = [int(i) for i in input().split()]




spuys_of_sums = [0]
spys = []

for ind in range(1,len(y)):

    for ind1 in range(ind,len(y)):
        new_prv = 0
        if y[ind] != y[ind1]:
            new_prv = y[ind] + y[ind1]
        if new_prv != 0:
            if new_prv not in spuys_of_sums:

                spuys_of_sums.append(new_prv)


for all in range(len(spys)):
    cur = spys[all]
    for ind in range(all + 1,len(spys)):

        cur += spys[ind]

        if cur not in spuys_of_sums:

            spuys_of_sums.append(cur)





res = 0
new_bit = 0


for bit in range(len(spuys_of_sums)):

    new_bit = new_bit | spuys_of_sums[bit]

print(new_bit)