n=int(input())
L=1<<16
if n>=16:
  print(L-1)
  exit()
a=list(map(int,input().split()))
q=[0]*L
q[0]=1
for v in a:
  nq=[0]*L
  for i in range(L):
    if q[i]:
      u=v
      for j in range(16):
        nq[i|u]=1
        u=u//2+(1<<15)*(u%2)
  q=nq
print(max(i for i in range(L) if q[i]))