#include <bits/stdc++.h>
#pragma comment(linker, "/stack:16777216")
using namespace std;
const int INF = 1 << 30;
const int MAX = 1 << 17;
int n;
int A[MAX];
int L[MAX];
int R[MAX];
int main() {
  cin >> n;
  for (int i = (0); i < (n); ++i) scanf("%d", &A[i]);
  L[0] = -1;
  for (int i = (1); i < (n); ++i) {
    int j = i - 1;
    while (j >= 0 && A[j] <= A[i]) j = L[j];
    L[i] = j;
  }
  R[n - 1] = n;
  for (int i = n - 2; i >= 0; i--) {
    int j = i + 1;
    while (j < n && A[j] <= A[i]) j = R[j];
    R[i] = j;
  }
  int res = 0;
  for (int i = (0); i < (n); ++i) {
    if (L[i] != -1) res = max(res, A[i] ^ A[L[i]]);
    if (R[i] != n) res = max(res, A[i] ^ A[R[i]]);
  }
  cout << res << endl;
  return 0;
}

### Prompt

Please provide a Cpp coded solution to the problem described below:

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>
#pragma comment(linker, "/stack:16777216")
using namespace std;
const int INF = 1 << 30;
const int MAX = 1 << 17;
int n;
int A[MAX];
int L[MAX];
int R[MAX];
int main() {
  cin >> n;
  for (int i = (0); i < (n); ++i) scanf("%d", &A[i]);
  L[0] = -1;
  for (int i = (1); i < (n); ++i) {
    int j = i - 1;
    while (j >= 0 && A[j] <= A[i]) j = L[j];
    L[i] = j;
  }
  R[n - 1] = n;
  for (int i = n - 2; i >= 0; i--) {
    int j = i + 1;
    while (j < n && A[j] <= A[i]) j = R[j];
    R[i] = j;
  }
  int res = 0;
  for (int i = (0); i < (n); ++i) {
    if (L[i] != -1) res = max(res, A[i] ^ A[L[i]]);
    if (R[i] != n) res = max(res, A[i] ^ A[R[i]]);
  }
  cout << res << endl;
  return 0;
}

```