import sys
input=lambda:sys.stdin.readline().rstrip()
N=int(input())
A=list(map(int,input().split()))
if N>15:
	print(2**16-1)
else:
	pos=[i==0 for i in range(2**16)]
	for i in A:
		temp=i
		newpos=[i==0 for i in range(2**16)]
		for k in range(16):
			temp=(temp//2)+(2**15)*(temp%2)
			for j in range(2**16):
				if pos[j]:
					newpos[j|temp]=1
		pos=newpos
	for i in range(2**16-1,-1,-1):
		if pos[i]:
			print(i)
			break