#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, i, j, lucky, mxInTemp = 0, ct = 0;
  cin >> n;
  long long ar[n];
  for (i = 0; i < n; i++) {
    cin >> ar[i];
  }
  stack<long long> go;
  stack<long long> temp;
  go.push(ar[0]);
  go.push(ar[1]);
  lucky = ar[0] ^ ar[1];
  long long templucky = 0;
  for (i = 2; i < n; i++) {
    mxInTemp = 0;
    ct = 0;
    while (go.size()) {
      if (go.top() > ar[i]) {
        ct++;
        if (ct < 2) {
          templucky = go.top() ^ ar[i];
          temp.push(go.top());
          go.pop();
          mxInTemp = temp.top();
          if (templucky > lucky) {
            lucky = templucky;
          }
        } else {
          break;
        }
      } else {
        if (go.top() > mxInTemp) {
          mxInTemp = go.top();
          templucky = go.top() ^ ar[i];
          temp.push(go.top());
          go.pop();
          if (templucky > lucky) {
            lucky = templucky;
          }
        } else {
          go.pop();
        }
      }
    }
    while (temp.size()) {
      go.push(temp.top());
      temp.pop();
    }
    go.push(ar[i]);
  }
  cout << lucky;
}

### Prompt

Generate 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 main() {
  long long n, i, j, lucky, mxInTemp = 0, ct = 0;
  cin >> n;
  long long ar[n];
  for (i = 0; i < n; i++) {
    cin >> ar[i];
  }
  stack<long long> go;
  stack<long long> temp;
  go.push(ar[0]);
  go.push(ar[1]);
  lucky = ar[0] ^ ar[1];
  long long templucky = 0;
  for (i = 2; i < n; i++) {
    mxInTemp = 0;
    ct = 0;
    while (go.size()) {
      if (go.top() > ar[i]) {
        ct++;
        if (ct < 2) {
          templucky = go.top() ^ ar[i];
          temp.push(go.top());
          go.pop();
          mxInTemp = temp.top();
          if (templucky > lucky) {
            lucky = templucky;
          }
        } else {
          break;
        }
      } else {
        if (go.top() > mxInTemp) {
          mxInTemp = go.top();
          templucky = go.top() ^ ar[i];
          temp.push(go.top());
          go.pop();
          if (templucky > lucky) {
            lucky = templucky;
          }
        } else {
          go.pop();
        }
      }
    }
    while (temp.size()) {
      go.push(temp.top());
      temp.pop();
    }
    go.push(ar[i]);
  }
  cout << lucky;
}

```