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 ans;
inline void dfs(vector<int>& a) {
  stack<int> s;
  for (int i = 0; i < a.size(); i++) {
    int v = a[i];
    while (s.size() && s.top() < v) s.pop();
    s.push(v);
    if (s.size() > 1) {
      int nm = s.top();
      s.pop();
      ans = max(ans, nm ^ s.top());
      s.push(nm);
    }
  }
}
inline void solve() {
  int n;
  scanf("%d", &n);
  vector<int> a(n);
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  ans = a[0] ^ a[1];
  dfs(a);
  reverse(a.begin(), a.end());
  dfs(a);
  cout << ans;
}
int main() {
  int t = 1;
  while (t--) solve();
  return 0;
}
