#include <bits/stdc++.h>
using namespace std;
int n;
int a[100050];
int main() {
  istream& in = cin;
  in >> n;
  for (int i = 0; i < n; i++) {
    in >> a[i];
  }
  int bits[30];
  memset(bits, 0, sizeof(bits));
  for (int i = 0; i < 30; i++) {
    int b = 1 << i;
    for (int j = 0; j < n; j++) {
      bits[i] += ((a[j] & b) != 0);
    }
  }
  int m = 0;
  int msb = 0;
  for (int i = 29; i >= 0; i--) {
    if (bits[i] == n) {
      m |= (1 << i);
    } else if (bits[i] != 0) {
      msb = 1 << i;
      break;
    }
  }
  for (int i = 0; i < n; i++) {
    a[i] -= m;
  }
  int res = 0;
  for (int i = 0; i < n;) {
    if (a[i] & msb) {
      int first = a[i];
      int j = i - 1;
      int second = 0;
      for (; j >= 0 && (a[j] & msb) == 0; j--) {
        if (a[j] >= second) {
          second = a[j];
          res = max(res, first ^ second);
        }
      }
      j = i + 1;
      second = 0;
      for (; j < n && (a[j] & msb) == 0; j++) {
        if (a[j] >= second) {
          second = a[j];
          res = max(res, first ^ second);
        }
      }
      i = j;
    } else {
      i++;
    }
  }
  cout << res << endl;
}

### 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 n;
int a[100050];
int main() {
  istream& in = cin;
  in >> n;
  for (int i = 0; i < n; i++) {
    in >> a[i];
  }
  int bits[30];
  memset(bits, 0, sizeof(bits));
  for (int i = 0; i < 30; i++) {
    int b = 1 << i;
    for (int j = 0; j < n; j++) {
      bits[i] += ((a[j] & b) != 0);
    }
  }
  int m = 0;
  int msb = 0;
  for (int i = 29; i >= 0; i--) {
    if (bits[i] == n) {
      m |= (1 << i);
    } else if (bits[i] != 0) {
      msb = 1 << i;
      break;
    }
  }
  for (int i = 0; i < n; i++) {
    a[i] -= m;
  }
  int res = 0;
  for (int i = 0; i < n;) {
    if (a[i] & msb) {
      int first = a[i];
      int j = i - 1;
      int second = 0;
      for (; j >= 0 && (a[j] & msb) == 0; j--) {
        if (a[j] >= second) {
          second = a[j];
          res = max(res, first ^ second);
        }
      }
      j = i + 1;
      second = 0;
      for (; j < n && (a[j] & msb) == 0; j++) {
        if (a[j] >= second) {
          second = a[j];
          res = max(res, first ^ second);
        }
      }
      i = j;
    } else {
      i++;
    }
  }
  cout << res << endl;
}

```