Bike loves looking for the second maximum element in the sequence. The second maximum element in the sequence of distinct numbers x1, x2, ..., xk (k > 1) is such maximum element xj, that the following inequality holds: <image>.

The lucky number of the sequence of distinct positive integers x1, x2, ..., xk (k > 1) is the number that is equal to the bitwise excluding OR of the maximum element of the sequence and the second maximum element of the sequence.

You've got a sequence of distinct positive integers s1, s2, ..., sn (n > 1). Let's denote sequence sl, sl + 1, ..., sr as s[l..r] (1 ≤ l < r ≤ n). Your task is to find the maximum number among all lucky numbers of sequences s[l..r].

Note that as all numbers in sequence s are distinct, all the given definitions make sence.

Input

The first line contains integer n (1 < n ≤ 105). The second line contains n distinct integers s1, s2, ..., sn (1 ≤ si ≤ 109).

Output

Print a single integer — the maximum lucky number among all lucky numbers of sequences s[l..r].

Examples

Input

5
5 2 1 4 3


Output

7


Input

5
9 8 3 5 7


Output

15

Note

For the first sample you can choose s[4..5] = {4, 3} and its lucky number is (4 xor 3) = 7. You can also choose s[1..2].

For the second sample you must choose s[2..5] = {8, 3, 5, 7}.
n = int(input().strip())
l = list(map(int,input().strip().split(' ')))

stk = []
maxVal = 0

stk.append(l[0])
stk.append(l[1])

maxVal = stk[-1]^stk[-2]

for i in l[2:]:
	while(len(stk) and stk[-1]<i):
		stk.pop()
	stk.append(i)
	#print(stk)
	if(len(stk)>=2):
		maxVal = max(maxVal, stk[-1]^stk[-2])
		

l = l[::-1]
stk = []
stk.append(l[0])
stk.append(l[1])

maxVal = max(maxVal, stk[-1]^stk[-2])
#print('')
for i in l[2:]:
	while(len(stk) and stk[-1]<i):
		stk.pop()
	stk.append(i)
	#print(stk)
	if(len(stk)>=2):
		maxVal = max(maxVal, stk[-1]^stk[-2])
		
print(maxVal)
