#include <bits/stdc++.h>
using namespace std;
int res;
set<int> si;
int s[100010];
vector<pair<int, int> > ss;
void sol(int id) {
  si.insert(id);
  set<int>::iterator it = si.lower_bound(id);
  if (it != si.begin()) {
    res = max(res, s[*it] ^ s[*(--it)]);
    ++it;
  }
  if (++it != si.end()) {
    res = max(res, s[*it] ^ s[*(--it)]);
  }
  return;
}
int main() {
  int n;
  cin >> n;
  ss.resize(n);
  for (int i = (0); i < (n); i++) cin >> s[i];
  for (int i = (0); i < (n); i++) {
    ss[i].first = -s[i];
    ss[i].second = i;
  }
  sort((ss).begin(), (ss).end());
  res = 0;
  si.clear();
  for (int i = (0); i < (n); i++) sol(ss[i].second);
  cout << res << endl;
  return 0;
}

### Prompt

Please formulate a Cpp solution to the following problem:

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}.

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
int res;
set<int> si;
int s[100010];
vector<pair<int, int> > ss;
void sol(int id) {
  si.insert(id);
  set<int>::iterator it = si.lower_bound(id);
  if (it != si.begin()) {
    res = max(res, s[*it] ^ s[*(--it)]);
    ++it;
  }
  if (++it != si.end()) {
    res = max(res, s[*it] ^ s[*(--it)]);
  }
  return;
}
int main() {
  int n;
  cin >> n;
  ss.resize(n);
  for (int i = (0); i < (n); i++) cin >> s[i];
  for (int i = (0); i < (n); i++) {
    ss[i].first = -s[i];
    ss[i].second = i;
  }
  sort((ss).begin(), (ss).end());
  res = 0;
  si.clear();
  for (int i = (0); i < (n); i++) sol(ss[i].second);
  cout << res << endl;
  return 0;
}

```