import sys
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
INF = 2**63-1
mod = 998244353
n = ii()

a = li()

if n >= 16:
    print(2 ** 16 - 1)
else:
    dp = [[False] * (2 ** 16) for _ in range(n + 1)]
    dp[0][0] = True
    for i in range(n):
        for j in range(2 ** 16):
            for k in range(16):
                dp[i + 1][j] |= dp[i][j]
                dp[i + 1][j | a[i]] |= dp[i][j]
                a[i] = a[i] // 2 + 2 ** 15 * (a[i] % 2)
    ans = 0
    for i in range(2**16):
        if dp[n][i]:
            ans = max(ans, i)
    print(ans)