#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> a(n, 0);
  for (int i = 0; i < n; i += 1) cin >> a[i];
  int chosen = -1;
  for (int bit = 30; bit >= 0; bit -= 1) {
    bool all = true;
    bool some = false;
    for (int i = 0; i < n; i += 1) {
      all &= (((1 << bit) & a[i]) > 0);
      some |= (((1 << bit) & a[i]) > 0);
    }
    if (not all and some) {
      chosen = bit;
      break;
    }
  }
  assert(chosen >= 0);
  vector<int> mark(n, 0);
  for (int i = 0; i < n; i += 1) {
    if ((a[i] & (1 << chosen)) > 0) {
      mark[i] = 1;
    }
  }
  int ans = 0;
  for (int i = 0; i < n; i += 1) {
    if (not mark[i]) continue;
    int maxx = 0;
    for (int j = i + 1; j < n and mark[j] == 0; j += 1) {
      maxx = max(maxx, a[j]);
      ans = max(ans, maxx xor a[i]);
    }
    maxx = 0;
    for (int j = i - 1; j >= 0 and mark[j] == 0; j -= 1) {
      maxx = max(maxx, a[j]);
      ans = max(ans, maxx xor a[i]);
    }
  }
  cout << ans << "\n";
}

### Prompt

Create a solution in CPP for 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;
int main() {
  int n;
  cin >> n;
  vector<int> a(n, 0);
  for (int i = 0; i < n; i += 1) cin >> a[i];
  int chosen = -1;
  for (int bit = 30; bit >= 0; bit -= 1) {
    bool all = true;
    bool some = false;
    for (int i = 0; i < n; i += 1) {
      all &= (((1 << bit) & a[i]) > 0);
      some |= (((1 << bit) & a[i]) > 0);
    }
    if (not all and some) {
      chosen = bit;
      break;
    }
  }
  assert(chosen >= 0);
  vector<int> mark(n, 0);
  for (int i = 0; i < n; i += 1) {
    if ((a[i] & (1 << chosen)) > 0) {
      mark[i] = 1;
    }
  }
  int ans = 0;
  for (int i = 0; i < n; i += 1) {
    if (not mark[i]) continue;
    int maxx = 0;
    for (int j = i + 1; j < n and mark[j] == 0; j += 1) {
      maxx = max(maxx, a[j]);
      ans = max(ans, maxx xor a[i]);
    }
    maxx = 0;
    for (int j = i - 1; j >= 0 and mark[j] == 0; j -= 1) {
      maxx = max(maxx, a[j]);
      ans = max(ans, maxx xor a[i]);
    }
  }
  cout << ans << "\n";
}

```