#include <bits/stdc++.h>
using namespace std;
long long int max(long long int a, long long int b) {
  if (a > b)
    return a;
  else
    return b;
}
long long int min(long long int a, long long int b) {
  if (a < b)
    return a;
  else
    return b;
}
const int dx[4] = {-1, 1, 0, 0};
const int dy[4] = {0, 0, -1, 1};
int XX[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int YY[] = {-1, 0, 1, -1, 1, -1, 0, 1};
long long int n;
long long int arr[100005];
long long int sparse[100005][30];
void buildSparseTableMin() {
  for (int i = 0; i < n; i++) sparse[i][0] = arr[i];
  for (int j = 1; (1 << j) <= n; j++) {
    for (int i = 0; (i + (1 << j) - 1) < n; i++)
      sparse[i][j] = max(sparse[i][j - 1], sparse[i + (1 << (j - 1))][j - 1]);
  }
}
int querymin(int L, int R) {
  int j = (int)log2(R - L + 1);
  return max(sparse[L][j], sparse[R - (1 << j) + 1][j]);
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  long long int m, t, r, i, j, x, l, y, w, h;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> arr[i];
  }
  long long int left[n];
  long long int right[n];
  for (i = 0; i < n; i++) {
    left[i] = -1;
    right[i] = n;
  }
  stack<long long int> s;
  for (i = 0; i < n; i++) {
    while (!s.empty() && arr[s.top()] < arr[i]) s.pop();
    if (!s.empty()) left[i] = s.top();
    s.push(i);
  }
  while (!s.empty()) s.pop();
  for (i = n - 1; i >= 0; i--) {
    while (!s.empty() && arr[s.top()] < arr[i]) s.pop();
    if (!s.empty()) right[i] = s.top();
    s.push(i);
  }
  long long int ans = 0;
  for (i = 0; i < n; i++) {
    long long int val = arr[i];
    long long int ind, val2;
    if (i + 1 < n && arr[i + 1] < arr[i]) {
      ans = max(ans, val ^ arr[i + 1]);
      long long int maxi = arr[i + 1];
      ind = right[i + 1];
      while (ind < n && arr[ind] < val) {
        ans = max(ans, val ^ arr[ind]);
        ind = right[ind];
      }
    }
    if (i - 1 >= 0 && arr[i - 1] < val) {
      ans = max(ans, val ^ arr[i - 1]);
      ind = left[i - 1];
      while (ind >= 0 && arr[ind] < val) {
        ans = max(ans, val ^ arr[ind]);
        ind = left[ind];
      }
    }
  }
  cout << ans;
}

### Prompt

Please formulate 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;
long long int max(long long int a, long long int b) {
  if (a > b)
    return a;
  else
    return b;
}
long long int min(long long int a, long long int b) {
  if (a < b)
    return a;
  else
    return b;
}
const int dx[4] = {-1, 1, 0, 0};
const int dy[4] = {0, 0, -1, 1};
int XX[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int YY[] = {-1, 0, 1, -1, 1, -1, 0, 1};
long long int n;
long long int arr[100005];
long long int sparse[100005][30];
void buildSparseTableMin() {
  for (int i = 0; i < n; i++) sparse[i][0] = arr[i];
  for (int j = 1; (1 << j) <= n; j++) {
    for (int i = 0; (i + (1 << j) - 1) < n; i++)
      sparse[i][j] = max(sparse[i][j - 1], sparse[i + (1 << (j - 1))][j - 1]);
  }
}
int querymin(int L, int R) {
  int j = (int)log2(R - L + 1);
  return max(sparse[L][j], sparse[R - (1 << j) + 1][j]);
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  long long int m, t, r, i, j, x, l, y, w, h;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> arr[i];
  }
  long long int left[n];
  long long int right[n];
  for (i = 0; i < n; i++) {
    left[i] = -1;
    right[i] = n;
  }
  stack<long long int> s;
  for (i = 0; i < n; i++) {
    while (!s.empty() && arr[s.top()] < arr[i]) s.pop();
    if (!s.empty()) left[i] = s.top();
    s.push(i);
  }
  while (!s.empty()) s.pop();
  for (i = n - 1; i >= 0; i--) {
    while (!s.empty() && arr[s.top()] < arr[i]) s.pop();
    if (!s.empty()) right[i] = s.top();
    s.push(i);
  }
  long long int ans = 0;
  for (i = 0; i < n; i++) {
    long long int val = arr[i];
    long long int ind, val2;
    if (i + 1 < n && arr[i + 1] < arr[i]) {
      ans = max(ans, val ^ arr[i + 1]);
      long long int maxi = arr[i + 1];
      ind = right[i + 1];
      while (ind < n && arr[ind] < val) {
        ans = max(ans, val ^ arr[ind]);
        ind = right[ind];
      }
    }
    if (i - 1 >= 0 && arr[i - 1] < val) {
      ans = max(ans, val ^ arr[i - 1]);
      ind = left[i - 1];
      while (ind >= 0 && arr[ind] < val) {
        ans = max(ans, val ^ arr[ind]);
        ind = left[ind];
      }
    }
  }
  cout << ans;
}

```