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;
vector<int> a;
list<int> v;
int main() {
  cin >> n;
  a.resize(n);
  for (int i = (int)(0); i < (int)(n); ++i) cin >> a[i];
  int maxd = -1, maxud = 0;
  bool all = true;
  do {
    for (int i = (int)(0); i < (int)(n); ++i) {
      bool got1 = false;
      for (int d = 31; d >= 0; --d) {
        if (d >= maxd && !got1 && (a[i] & (1 << d))) {
          got1 = true;
          if (maxd > -1 && d > maxd) all = false;
          maxd = max(d, maxd);
        } else if (!(a[i] & (1 << d)) && got1) {
          maxud = max(maxud, d);
          break;
        } else if (!(a[i] & (1 << d)) && i && maxd > d) {
          all = false;
          break;
        }
      }
      if (!got1) all = false;
    }
    if (all) {
      int mask = 0;
      for (int d = (int)(maxud + 1); d < (int)(maxd + 1); ++d) mask ^= (1 << d);
      for (int i = (int)(0); i < (int)(n); ++i) a[i] ^= mask;
      maxd = -1, maxud = 0;
    }
  } while (all);
  int res = 0;
  for (int i = (int)(0); i < (int)(n); ++i) {
    if (a[i] & (1 << maxd)) v.push_back(i);
  }
  int last = 0;
  for (auto it = v.begin(); it != v.end(); ++it) {
    auto nit = it;
    int next = ++nit == v.end() ? n : *nit;
    int maxx = -1;
    for (int i = *it - 1; i >= last; --i) {
      if (maxx < a[i]) {
        maxx = a[i];
        res = max(res, a[*it] ^ maxx);
      }
    }
    maxx = -1;
    for (int i = *it + 1; i < next; ++i) {
      if (maxx < a[i]) {
        maxx = a[i];
        res = max(res, a[*it] ^ maxx);
      }
    }
    last = *it + 1;
  }
  cout << res << endl;
  return 0;
}
