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 a[100000];
int n;
int res = 0;
int s[100000];
int t[100000];
void solve(int l, int r) {
  if (r - l <= 1) return;
  int m = (l + r) / 2;
  solve(l, m);
  solve(m, r);
  int S = 0;
  s[S++] = a[m - 1];
  for (int i = m - 2; i >= l; i--) {
    if (s[S - 1] < a[i]) {
      s[S++] = a[i];
    }
  }
  int T = 0;
  t[T++] = a[m];
  for (int i = m + 1; i < r; i++) {
    if (t[T - 1] < a[i]) {
      t[T++] = a[i];
    }
  }
  for (int i = 0; i < (int)S; i++) {
    int higher = s[i];
    int lower = i ? s[i - 1] : -1;
    higher = lower_bound(t, t + T, higher) - t;
    lower = lower_bound(t, t + T, lower) - t;
    for (int q = lower; q < higher; q++) {
      res = max(res, s[i] ^ t[q]);
    }
  }
  for (int i = 0; i < (int)T; i++) {
    int higher = t[i];
    int lower = i ? t[i - 1] : -1;
    higher = lower_bound(s, s + S, higher) - s;
    lower = lower_bound(s, s + S, lower) - s;
    for (int q = lower; q < higher; q++) {
      res = max(res, s[q] ^ t[i]);
    }
  }
}
int correct() {
  int ans = 0;
  vector<int> ttt;
  for (int i = 0; i < (int)n; i++) {
    ttt.push_back(a[i]);
  }
  sort(ttt.begin(), ttt.end());
  for (int r = 0; r < (int)n + 1; r++) {
    for (int l = 0; l < (int)r; l++) {
      vector<int> t;
      for (int i = l; i < r; i++) {
        t.push_back(a[i]);
      }
      sort(t.rbegin(), t.rend());
      if (r - l <= 1) continue;
      ans = max(ans, t[0] ^ t[1]);
      if (ans == (t[0] ^ t[1])) {
      }
    }
  }
  return ans;
}
int main() {
  while (cin >> n) {
    for (int i = 0; i < (int)n; i++) cin >> a[i];
    res = 0;
    solve(0, n);
    cout << res << endl;
  }
  return 0;
}
