#include <bits/stdc++.h>
int dx[] = {+0, +0, -1, +1, +1, +1, -1, -1};
int dy[] = {+1, -1, +0, +0, +1, -1, +1, -1};
using namespace std;
int n, k, a[100000 + 5], res, A, B;
int main() {
  scanf("%d", &n);
  for (int i = int(1); i <= int(n); i++) scanf("%d", &a[i]);
  k = 0;
  for (int i = int(31 - 1); i >= 0; i--) {
    for (int j = int(2); j <= int(n); j++)
      if ((a[j] & (1 << i)) != (a[j - 1] & (1 << i))) {
        k = i;
        break;
      }
    if (k != 0) break;
  }
  res = A = B = 0;
  for (int i = int(1); i <= int(n); i++) {
    if (a[i] & (1 << k)) {
      A = a[i];
      B = 0;
      continue;
    }
    B = max(a[i], B);
    if (A > 0) res = max(res, A ^ B);
  }
  A = B = 0;
  for (int i = int(n); i >= int(1); i--) {
    if (a[i] & (1 << k)) {
      A = a[i];
      B = 0;
      continue;
    }
    B = max(a[i], B);
    if (A > 0) res = max(res, A ^ B);
  }
  cout << res << endl;
  return 0;
}

### Prompt

Please create a solution in Cpp 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>
int dx[] = {+0, +0, -1, +1, +1, +1, -1, -1};
int dy[] = {+1, -1, +0, +0, +1, -1, +1, -1};
using namespace std;
int n, k, a[100000 + 5], res, A, B;
int main() {
  scanf("%d", &n);
  for (int i = int(1); i <= int(n); i++) scanf("%d", &a[i]);
  k = 0;
  for (int i = int(31 - 1); i >= 0; i--) {
    for (int j = int(2); j <= int(n); j++)
      if ((a[j] & (1 << i)) != (a[j - 1] & (1 << i))) {
        k = i;
        break;
      }
    if (k != 0) break;
  }
  res = A = B = 0;
  for (int i = int(1); i <= int(n); i++) {
    if (a[i] & (1 << k)) {
      A = a[i];
      B = 0;
      continue;
    }
    B = max(a[i], B);
    if (A > 0) res = max(res, A ^ B);
  }
  A = B = 0;
  for (int i = int(n); i >= int(1); i--) {
    if (a[i] & (1 << k)) {
      A = a[i];
      B = 0;
      continue;
    }
    B = max(a[i], B);
    if (A > 0) res = max(res, A ^ B);
  }
  cout << res << endl;
  return 0;
}

```