#include <bits/stdc++.h>
using namespace std;
const int V = 100100;
int l[V], r[V], a[V], ret, n;
int main() {
  while (~scanf("%d", &n)) {
    ret = 0;
    for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
    for (int i = 1; i <= n; i++) l[i] = r[i] = i;
    for (int i = 1; i <= n; i++) {
      while (l[i] != 1 && a[l[i] - 1] < a[i]) l[i] = l[l[i] - 1];
      if (l[i] != 1) ret = max(ret, a[i] ^ a[l[i] - 1]);
    }
    for (int i = n; i >= 1; i--) {
      while (r[i] != n && a[r[i] + 1] < a[i]) r[i] = r[r[i] + 1];
      if (r[i] != n) ret = max(ret, a[i] ^ a[r[i] + 1]);
    }
    printf("%d\n", ret);
  }
}

### 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>
using namespace std;
const int V = 100100;
int l[V], r[V], a[V], ret, n;
int main() {
  while (~scanf("%d", &n)) {
    ret = 0;
    for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
    for (int i = 1; i <= n; i++) l[i] = r[i] = i;
    for (int i = 1; i <= n; i++) {
      while (l[i] != 1 && a[l[i] - 1] < a[i]) l[i] = l[l[i] - 1];
      if (l[i] != 1) ret = max(ret, a[i] ^ a[l[i] - 1]);
    }
    for (int i = n; i >= 1; i--) {
      while (r[i] != n && a[r[i] + 1] < a[i]) r[i] = r[r[i] + 1];
      if (r[i] != n) ret = max(ret, a[i] ^ a[r[i] + 1]);
    }
    printf("%d\n", ret);
  }
}

```