B. Maximum Xor Secondarytime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputBike 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: .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.InputThe first line contains integer n (1 < n ≤ 105). The second line contains n distinct integers s1, s2, ..., sn (1 ≤ si ≤ 109).OutputPrint a single integer — the maximum lucky number among all lucky numbers of sequences s[l..r].ExamplesInput55 2 1 4 3Output7Input59 8 3 5 7Output15NoteFor 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}.
Input55 2 1 4 3
Output7
['data structures', 'implementation', 'two pointers', '*1800']