n = int(input())
a = list(map(int,input().split()))
b = [0]*((1<<16)+10)

def f(x):
  return x//2 + pow(2,15)*(x%2)
b[0] = 1
for i in range(min(n, 20)):
  now = a[i]
  new = [0]*((1<<16)+10)
  new[0] = 1
  for j in range(20):
    tmp = f(now)
    for k in range((1<<16)+10):
      if b[k]:
        new[k|tmp] = 1
    now = tmp
  b = new[::1]
for i in range((1<<16)+10)[::-1]:
  if b[i]:
    print(i)
    exit()