#include <bits/stdc++.h>
struct node {
  long long int val;
  struct node* next;
};
struct node* push(int value, struct node* head) {
  struct node* temp = (struct node*)malloc(sizeof(struct node));
  temp->val = value;
  temp->next = head;
  return temp;
}
void pri(struct node* head) {
  printf("*");
  while (head) {
    printf("%lld ", head->val);
    head = head->next;
  }
  printf("*");
}
struct node* pop(struct node* head) {
  head = head->next;
  return head;
}
int main() {
  long long int n;
  scanf("%lld *", &n);
  long long int max = 0;
  long long int* ar = (long long int*)malloc(n * sizeof(long long int));
  struct node* head = NULL;
  for (int i = 0; i < n; i++) scanf("%lld", ar + i);
  head = push(ar[0], head);
  for (int i = 1; i - n; i++) {
    if (head && head->val < ar[i]) {
      while (head && head->val < ar[i]) {
        max = (head->val ^ ar[i]) > max ? (head->val ^ ar[i]) : max;
        head = pop(head);
      }
    }
    if (head) max = (head->val ^ ar[i]) > max ? (head->val ^ ar[i]) : max;
    head = push(ar[i], head);
  }
  printf("%lld\n", max);
}

### 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>
struct node {
  long long int val;
  struct node* next;
};
struct node* push(int value, struct node* head) {
  struct node* temp = (struct node*)malloc(sizeof(struct node));
  temp->val = value;
  temp->next = head;
  return temp;
}
void pri(struct node* head) {
  printf("*");
  while (head) {
    printf("%lld ", head->val);
    head = head->next;
  }
  printf("*");
}
struct node* pop(struct node* head) {
  head = head->next;
  return head;
}
int main() {
  long long int n;
  scanf("%lld *", &n);
  long long int max = 0;
  long long int* ar = (long long int*)malloc(n * sizeof(long long int));
  struct node* head = NULL;
  for (int i = 0; i < n; i++) scanf("%lld", ar + i);
  head = push(ar[0], head);
  for (int i = 1; i - n; i++) {
    if (head && head->val < ar[i]) {
      while (head && head->val < ar[i]) {
        max = (head->val ^ ar[i]) > max ? (head->val ^ ar[i]) : max;
        head = pop(head);
      }
    }
    if (head) max = (head->val ^ ar[i]) > max ? (head->val ^ ar[i]) : max;
    head = push(ar[i], head);
  }
  printf("%lld\n", max);
}

```