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;
template <typename T>
void show(T *a, int size) {
  int i;
  cout << endl << "The array is ";
  for (long long i = 0; i < size; ++i) {
    cout << a[i] << " ";
  }
  cout << endl;
}
template <typename T>
void show_vector(vector<T> v) {
  cout << endl << "The vector is ";
  int i;
  for (long long i = 0; i < v.size(); ++i) {
    cout << v[i] << " ";
  }
  cout << endl;
}
long long int a[100005], n;
long long int func() {
  stack<long long int> s;
  s.push(a[0]);
  long long int ans = 0;
  for (long long i = 1; i < n; ++i) {
    while (!s.empty() && a[i] > s.top()) {
      ans = max(ans, a[i] ^ s.top());
      s.pop();
    }
    if (!s.empty()) {
      ans = max(ans, a[i] ^ s.top());
    }
    s.push(a[i]);
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (long long i = 0; i < n; ++i) {
    cin >> a[i];
  }
  cout << func() << endl;
  return 0;
}
