#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 5;
int a[MAXN];
void solve() {
  int n;
  scanf("%d", &n);
  int ans = 0;
  stack<int> st;
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }
  for (int i = 0; i < n; i++) {
    if (st.empty()) {
      st.push(a[i]);
      continue;
    }
    while (!st.empty()) {
      int top = st.top();
      ans = max(ans, top ^ a[i]);
      if (top < a[i]) {
        st.pop();
      } else
        break;
    }
    st.push(a[i]);
  }
  cout << ans;
}
int main() {
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}

### Prompt

Please create a solution in CPP 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;
const int MAXN = 1e5 + 5;
int a[MAXN];
void solve() {
  int n;
  scanf("%d", &n);
  int ans = 0;
  stack<int> st;
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }
  for (int i = 0; i < n; i++) {
    if (st.empty()) {
      st.push(a[i]);
      continue;
    }
    while (!st.empty()) {
      int top = st.top();
      ans = max(ans, top ^ a[i]);
      if (top < a[i]) {
        st.pop();
      } else
        break;
    }
    st.push(a[i]);
  }
  cout << ans;
}
int main() {
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}

```