N=int(input())
A=list(map(int, input().split()))
if N>15:
  print(2**16-1)
  exit()
from collections import deque
D=[0]*(2**16)
D[0]=1
d=deque()
d.append(0)
def f(x):
  return x//2+(2**15)*(x%2)

for i in range(N):
  nd=deque()
  while d:
    now=d.popleft()
    a=A[i]
    nd.append(now)
    for j in range(16):
      dd=now|a
      if D[dd]==0:
        D[dd]=1
        nd.append(dd)
      a=f(a)
  d=nd

ans=0
for i in range(2**16):
  if D[i]==1:
    ans=max(ans,i)
print(ans)