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}.
def brute_force_max_lucky(values):
    cur_max = float('-inf')
    A = []
    for value in values:
        A.append((value, float('-inf')))
    for size in xrange(1, len(values) + 1):
        for index, value in enumerate(values[size:]):
            biggest, smallest = A[index]
            if value > biggest:
                A[index] = (value, biggest)
            elif value > smallest:
                A[index] = (biggest, value)
            cur_max = max(cur_max, A[index][0] ^ A[index][1])
    
    return cur_max

class DoubleLinkedObject(object):
    def __init__(self, value, left_index, right_index):
        self.value = value
        self.left_index = left_index
        self.right_index = right_index

def find_max_lucky(values):
    value_count = len(values)
    linked_list = []
    for index, value in enumerate(values):
        if index == 0:
            # there are at least 2 objects
            new_object = DoubleLinkedObject(value, None, index + 1)
        elif index == value_count - 1:
            new_object = DoubleLinkedObject(value, index - 1, None)
        else:
            new_object = DoubleLinkedObject(value, index - 1, index + 1)
        linked_list.append(new_object)
        
    cur_max = float('-inf')
    for index in (index for (value, index) in sorted(list((value, index) for index, value in enumerate(values)))):
        if linked_list[index].left_index is not None:
            cur_max = max(cur_max, linked_list[index].value ^ linked_list[linked_list[index].left_index].value)
            linked_list[linked_list[index].left_index].right_index = linked_list[index].right_index
        if linked_list[index].right_index is not None:
            cur_max = max(cur_max, linked_list[index].value ^ linked_list[linked_list[index].right_index].value)
            linked_list[linked_list[index].right_index].left_index = linked_list[index].left_index
    return cur_max

def main():
    value_count = int(raw_input())
    values = map(int, raw_input().split())
    print find_max_lucky(values)

if __name__ == '__main__':
    main()
