N = int(input())
A = list(map(int, input().split()))
NM = 1 << 16
if N >= 16:
    print(NM - 1)
    exit()

dp = [0] * NM
dp[0] = 1
for a in A:
    dp2 = [0] * NM
    for i in range(16):
        for j in range(NM):
            dp2[j|a] |= dp[j]
        a = (a >> 1) | ((a & 1) << 15)
    dp = dp2
for i in reversed(range(NM)):
    if dp[i] == 1:
        break
print(i)