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}.
#include <bits/stdc++.h>
using namespace std;
int n;
int arr[100005];
int leftBIT[100005], rightBIT[100005];
map<int, int> compress;
int reverse_map[100005];
void updateLeft(int idx, int val) {
  while (idx <= n) {
    leftBIT[idx] = min(leftBIT[idx], val);
    idx += idx & (-idx);
  }
}
void updateRight(int idx, int val) {
  while (idx <= n) {
    rightBIT[idx] = max(rightBIT[idx], val);
    idx += idx & (-idx);
  }
}
int queryLeft(int idx) {
  int ans = n + 1;
  while (idx) {
    ans = min(ans, leftBIT[idx]);
    idx -= idx & (-idx);
  }
  return ans;
}
int queryRight(int idx) {
  int ans = 0;
  while (idx) {
    ans = max(ans, rightBIT[idx]);
    idx -= idx & (-idx);
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  int i, ans, temp;
  cin >> n;
  for (i = 1; i <= n; i++) {
    cin >> arr[i];
    reverse_map[i] = arr[i];
  }
  sort(reverse_map + 1, reverse_map + n + 1);
  for (i = 1; i <= n; i++) compress[reverse_map[i]] = n + 1 - i;
  for (i = 1; i <= n; i++)
    if (n + 1 - i > i) swap(reverse_map[i], reverse_map[n + 1 - i]);
  for (i = 0; i <= 100000; i++) {
    leftBIT[i] = n + 1;
    rightBIT[i] = 0;
  }
  ans = 0;
  for (i = 1; i <= n; i++) {
    int actual = compress[arr[i]];
    int leftPos = queryRight(actual - 1);
    if (leftPos != 0 && leftPos != i) ans = max(ans, arr[leftPos] ^ arr[i]);
    updateRight(actual, i);
  }
  for (i = n; i >= 1; i--) {
    int actual = compress[arr[i]];
    int rightPos = queryLeft(actual - 1);
    if (rightPos != n + 1 && i != rightPos)
      ans = max(ans, arr[i] ^ arr[rightPos]);
    updateLeft(actual, i);
  }
  cout << ans;
  return 0;
}
