#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e6 + 5, mod = 1e9 + 7, inf = 1e9 + 7;
const ll INF = 1e18 + 5;
int a[N];
int main() {
  ios ::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  for (int i = 1; i <= n; ++i) cin >> a[i];
  int res = 0;
  for (int lol = 30; lol >= 0; lol--) {
    for (int i = 1; i <= n; ++i) {
      if ((a[i] >> lol) & 1) {
        int f = -1;
        int mx = 0;
        for (int j = i - 1; j >= 1; j--) {
          if ((a[j] >> lol) & 1 || a[j] >= a[i]) {
            f = j + 1;
            break;
          }
          if (j == 1) f = j;
          mx = max(mx, a[j]);
          res = max(res, (mx ^ a[i]));
        }
        int s = -1;
        for (int j = i + 1; j <= n; ++j) {
          if ((a[j] >> lol) & 1 || a[j] >= a[i]) {
            s = j - 1;
            break;
          }
          if (j == n) s = j;
          mx = max(mx, a[j]);
          res = max(res, (mx ^ a[i]));
        }
      }
    }
  }
  cout << res;
  return 0;
}

### Prompt

Please formulate 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;
using ll = long long;
const int N = 1e6 + 5, mod = 1e9 + 7, inf = 1e9 + 7;
const ll INF = 1e18 + 5;
int a[N];
int main() {
  ios ::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  for (int i = 1; i <= n; ++i) cin >> a[i];
  int res = 0;
  for (int lol = 30; lol >= 0; lol--) {
    for (int i = 1; i <= n; ++i) {
      if ((a[i] >> lol) & 1) {
        int f = -1;
        int mx = 0;
        for (int j = i - 1; j >= 1; j--) {
          if ((a[j] >> lol) & 1 || a[j] >= a[i]) {
            f = j + 1;
            break;
          }
          if (j == 1) f = j;
          mx = max(mx, a[j]);
          res = max(res, (mx ^ a[i]));
        }
        int s = -1;
        for (int j = i + 1; j <= n; ++j) {
          if ((a[j] >> lol) & 1 || a[j] >= a[i]) {
            s = j - 1;
            break;
          }
          if (j == n) s = j;
          mx = max(mx, a[j]);
          res = max(res, (mx ^ a[i]));
        }
      }
    }
  }
  cout << res;
  return 0;
}

```