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;
struct node {
  int x, y, mx, mn;
};
int N;
vector<int> v;
node a[1000008];
void initialize(int ind, int start, int end) {
  if (start == end) {
    a[ind].x = a[ind].y = start;
    a[ind].mx = v[start];
    a[ind].mn = 0;
  } else {
    int mid = (start + end) / 2;
    initialize(ind * 2, start, mid);
    initialize(ind * 2 + 1, mid + 1, end);
    a[ind].mx = max(a[ind * 2].mx, a[ind * 2 + 1].mx);
    if (a[ind].mx == a[ind * 2].mx) {
      a[ind].mn = max(a[ind * 2].mn, a[ind * 2 + 1].mx);
      a[ind].x = a[ind * 2].x;
      if (a[ind].mn == a[ind * 2].mn)
        a[ind].y = a[ind * 2].y;
      else
        a[ind].y = a[ind * 2 + 1].x;
    } else {
      a[ind].mn = max(a[ind * 2 + 1].mn, a[ind * 2].mx);
      a[ind].x = a[ind * 2 + 1].x;
      if (a[ind].mn == a[ind * 2].mx)
        a[ind].y = a[ind * 2].x;
      else
        a[ind].y = a[ind * 2 + 1].y;
    }
  }
}
node query(int ind, int i, int j, int start, int end) {
  if (i <= start && j >= end) return a[ind];
  int mid = (start + end) / 2;
  if (j <= mid)
    return query(ind * 2, i, j, start, mid);
  else if (i > mid)
    return query(ind * 2 + 1, i, j, mid + 1, end);
  else {
    node p1, p2, p3;
    p1 = query(ind * 2, i, j, start, mid);
    p2 = query(ind * 2 + 1, i, j, mid + 1, end);
    p3.mx = max(p1.mx, p2.mx);
    if (p3.mx == p1.mx) {
      p3.mn = max(p1.mn, p2.mx);
      p3.x = p1.x;
      if (p3.mn == p1.mn)
        p3.y = p1.y;
      else
        p3.y = p2.x;
    } else {
      p3.mn = max(p2.mn, p1.mx);
      p3.x = p2.x;
      if (p3.mn == p1.mx)
        p3.y = p1.x;
      else
        p3.y = p2.y;
    }
    return p3;
  }
}
map<map<int, int>, int> dp;
int ans(int i, int j) {
  if (i >= j) return 0;
  map<int, int> mp;
  mp[i] = j;
  if (dp.count(mp) > 0) return dp[mp];
  node p = query(1, i - 1, j - 1, 0, N - 1);
  int as = p.mx ^ p.mn;
  as = max(as, max(ans(i, max(p.x, p.y)), ans(min(p.x, p.y) + 2, j)));
  as = max(as, ans(min(p.x, p.y) + 2, max(p.x, p.y)));
  dp[mp] = as;
  return as;
}
int main() {
  int n;
  cin >> n;
  N = n;
  v.resize(n);
  for (int i = 0; i < n; i++) scanf("%d", &v[i]);
  initialize(1, 0, n - 1);
  cout << ans(1, n) << "\n";
  return 0;
}
