n = int(input())
if n >= 16:
    print((1 << 16) - 1)
    exit()

A = list(map(int, input().split()))
DP = [[False for _ in range(1 << 16)] for _ in range(n + 1)]
header = 1 << 15
for i in range(n + 1):
    DP[i][0] = True
for i in range(n):
    a = A[i]
    for j in range(16):
        for k in range(1 << 16):
            if DP[i][k]:
                DP[i + 1][k | a] |= DP[i][k]
        a, r = divmod(a, 2)
        a |= header * r
for i in range((1 << 16) - 1, 0, -1):
    if DP[n][i]:
        print(i)
        break