#include <bits/stdc++.h>
using namespace std;
const long long maxn = 1e5 + 5;
long long fir_max_L[maxn], fir_max_R[maxn], A[maxn], n;
void get_max_LR() {
  vector<long long> v;
  v.push_back(2e12 + 7);
  for (long long i = 0; i < n; i++) {
    while (v.back() < A[i]) v.pop_back();
    fir_max_L[i] = v.back();
    v.push_back(A[i]);
  }
  v.clear();
  v.push_back(2e12 + 7);
  for (long long i = n - 1; i > -1; i--) {
    while (v.back() < A[i]) v.pop_back();
    fir_max_R[i] = v.back();
    v.push_back(A[i]);
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  long long ans = 0;
  for (long long i = 0; i < n; i++) cin >> A[i], ans = max(ans, A[i]);
  ans = 0;
  get_max_LR();
  for (long long i = 0; i < n; i++) {
    if (fir_max_L[i] < 2e12 + 7) ans = max(ans, A[i] ^ fir_max_L[i]);
    if (fir_max_R[i] < 2e12 + 7) ans = max(ans, A[i] ^ fir_max_R[i]);
  }
  cout << ans << endl;
  return 0;
}

### Prompt

Develop a solution in cpp to the problem described below:

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}.

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
const long long maxn = 1e5 + 5;
long long fir_max_L[maxn], fir_max_R[maxn], A[maxn], n;
void get_max_LR() {
  vector<long long> v;
  v.push_back(2e12 + 7);
  for (long long i = 0; i < n; i++) {
    while (v.back() < A[i]) v.pop_back();
    fir_max_L[i] = v.back();
    v.push_back(A[i]);
  }
  v.clear();
  v.push_back(2e12 + 7);
  for (long long i = n - 1; i > -1; i--) {
    while (v.back() < A[i]) v.pop_back();
    fir_max_R[i] = v.back();
    v.push_back(A[i]);
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  long long ans = 0;
  for (long long i = 0; i < n; i++) cin >> A[i], ans = max(ans, A[i]);
  ans = 0;
  get_max_LR();
  for (long long i = 0; i < n; i++) {
    if (fir_max_L[i] < 2e12 + 7) ans = max(ans, A[i] ^ fir_max_L[i]);
    if (fir_max_R[i] < 2e12 + 7) ans = max(ans, A[i] ^ fir_max_R[i]);
  }
  cout << ans << endl;
  return 0;
}

```