#include <bits/stdc++.h>
int stack[100000];
int stack_size = 0;
int s[100000];
int s_size = 0;
int main() {
  int i;
  scanf("%d", &s_size);
  for (i = 0; i < s_size; i++) scanf("%d", s + i);
  stack_size++;
  stack[stack_size - 1] = (s[0]);
  ;
  int maxlucky = 0;
  for (i = 1; i < s_size; i++) {
    while (stack_size > 0) {
      maxlucky = ((maxlucky) > (s[i] ^ stack[stack_size - 1])
                      ? (maxlucky)
                      : (s[i] ^ stack[stack_size - 1]));
      if (stack[stack_size - 1] > s[i])
        break;
      else
        stack_size--;
      ;
    }
    stack_size++;
    stack[stack_size - 1] = (s[i]);
    ;
  }
  printf("%d\n", maxlucky);
}

### Prompt

Your challenge is to write 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>
int stack[100000];
int stack_size = 0;
int s[100000];
int s_size = 0;
int main() {
  int i;
  scanf("%d", &s_size);
  for (i = 0; i < s_size; i++) scanf("%d", s + i);
  stack_size++;
  stack[stack_size - 1] = (s[0]);
  ;
  int maxlucky = 0;
  for (i = 1; i < s_size; i++) {
    while (stack_size > 0) {
      maxlucky = ((maxlucky) > (s[i] ^ stack[stack_size - 1])
                      ? (maxlucky)
                      : (s[i] ^ stack[stack_size - 1]));
      if (stack[stack_size - 1] > s[i])
        break;
      else
        stack_size--;
      ;
    }
    stack_size++;
    stack[stack_size - 1] = (s[i]);
    ;
  }
  printf("%d\n", maxlucky);
}

```