n=int(input())
a=list(map(int,input().split()))
m=1<<16
if n>=16:
  print(m-1)
  exit()

def shift(x):
  if x%2==1:
    return (1<<15)+x//2
  else:
    return x//2

ok=[0]*m
ok[0]=1

for ai in a:
  nok=[0]*m
  for _ in range(20):
    ai=shift(ai)
    for j in range(m):
      if ok[j]:
        nok[j|ai]=1
  
  ok=nok
ans=0
for i in range(m):
  if ok[i]:
    ans=i

print(ans)