#include <bits/stdc++.h>
using namespace std;
struct data {
  long long value;
  long long index;
};
bool comparedata(data i1, data i2) { return i1.value < i2.value; }
int main() {
  long long n, i, j, k, sum, p, s, maxf = 0, t, a[100005];
  map<long long, long long> m1;
  vector<data> v;
  vector<long long> graph[100005];
  map<long long, long long>::iterator it;
  map<long long, long long>::iterator itr;
  scanf("%lld", &n);
  for (i = 0; i < n; i++) {
    scanf("%lld", &a[i]);
    v.push_back({a[i], i});
  }
  sort(v.begin(), v.end(), comparedata);
  for (i = n - 1; i >= 0; i--) {
    m1[v[i].index];
    it = m1.find(v[i].index);
    itr = it;
    if (it != m1.begin()) itr--, graph[itr->first].push_back(v[i].index);
    it++;
    if (it != m1.end()) graph[it->first].push_back(v[i].index);
  }
  for (i = 0; i < n; i++) {
    for (j = 0; j < graph[i].size(); j++) {
      maxf = max(maxf, a[graph[i][j]] ^ a[i]);
    }
  }
  printf("%lld\n", maxf);
}

### Prompt

Your task is to create a Cpp solution to the following problem:

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;
struct data {
  long long value;
  long long index;
};
bool comparedata(data i1, data i2) { return i1.value < i2.value; }
int main() {
  long long n, i, j, k, sum, p, s, maxf = 0, t, a[100005];
  map<long long, long long> m1;
  vector<data> v;
  vector<long long> graph[100005];
  map<long long, long long>::iterator it;
  map<long long, long long>::iterator itr;
  scanf("%lld", &n);
  for (i = 0; i < n; i++) {
    scanf("%lld", &a[i]);
    v.push_back({a[i], i});
  }
  sort(v.begin(), v.end(), comparedata);
  for (i = n - 1; i >= 0; i--) {
    m1[v[i].index];
    it = m1.find(v[i].index);
    itr = it;
    if (it != m1.begin()) itr--, graph[itr->first].push_back(v[i].index);
    it++;
    if (it != m1.end()) graph[it->first].push_back(v[i].index);
  }
  for (i = 0; i < n; i++) {
    for (j = 0; j < graph[i].size(); j++) {
      maxf = max(maxf, a[graph[i][j]] ^ a[i]);
    }
  }
  printf("%lld\n", maxf);
}

```