n = int(input())
ress_array = []
ress_array.append(0)
ress_array.extend(input().split(" "))
full_sum = 0

for i in range(0, len(ress_array)):
    ress_array[i] = int(ress_array[i])
    full_sum += ress_array[i]

ress_array.append(full_sum)
length = len(ress_array)

for i in range(1, length):
    for j in range(i + 1, length - 1):
        sum = ress_array[i] + ress_array[j]
        # print(f"{ress_array[i]} + {ress_array[j]} = {sum}")
        if sum not in ress_array and sum <= ress_array[i] + ress_array[j]:
            ress_array.append(sum)
            # print(f"appended {ress_array}")

res = 0
for i in range(0, len(ress_array)):
    res |= ress_array[i]

print(res)