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;
const int N = 1e5 + 5;
int n, a[N], L[N], R[N];
void read_input() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
}
void solve() {
  for (int i = 0; i < n; i++) {
    L[i] = i - 1;
    while (~L[i] && a[L[i]] < a[i]) L[i] = L[L[i]];
  }
  for (int i = n - 1; ~i; i--) {
    R[i] = i + 1;
    while (R[i] < n && a[R[i]] < a[i]) R[i] = R[R[i]];
  }
}
void write_output() {
  int ans = 0;
  for (int i = 0; i < n; i++)
    for (auto x : {L[i], R[i]})
      if (~x && x < n) ans = max(ans, a[i] ^ a[x]);
  cout << ans;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  read_input(), solve(), write_output();
  return 0;
}
