N = int(input())
A = list(map(int,input().split()))
if N >= 16:
    print((1<<16)-1)
    exit()
dp = [[False] *(1<<16) for _ in range(N)]
def shift(x):
    return x//2 + (1<<15) *(x%2)
B = [[] for _ in range(N)]
for i in range(N):
    x = A[i]
    for _ in range(16):
        x = shift(x)
        B[i].append(x)
for x in B[0]:
    dp[0][x] = True
for i in range(N-1):
    for s in range(1<<16):
        if dp[i][s]:
            for x in B[i+1]:
                dp[i+1][s|x] = True
for s in reversed(range(1<<16)):
    if dp[N-1][s]:
        print(s)
        exit()