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}.
#include <bits/stdc++.h>
using namespace std;
long long int solve(vector<long long int> v, long long int n) {
  long long int i, r = v[0] ^ v[1];
  vector<long long int> s;
  for (i = 0; i < n; i++) {
    while (!s.empty() && s.back() < v[i]) s.pop_back();
    s.push_back(v[i]);
    if (s.size() >= 2) r = max(r, s[s.size() - 1] ^ s[s.size() - 2]);
  }
  return r;
}
int main() {
  long long int n, i, r, q;
  cin >> n;
  vector<long long int> v(n);
  for (i = 0; i < n; i++) cin >> v[i];
  r = solve(v, n);
  reverse(v.begin(), v.end());
  q = solve(v, n);
  r = max(r, q);
  cout << r << endl;
  return 0;
}
