#include <bits/stdc++.h>
const int MAXN = 1e5;
int n, ans, top;
int a[MAXN | 1], stack[MAXN | 1];
inline int read() {
  register int x = 0;
  register char ch = getchar();
  while (!isdigit(ch)) ch = getchar();
  while (isdigit(ch)) {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x;
}
int main() {
  n = read();
  for (int i = 1; i <= n; ++i) a[i] = read();
  for (int i = 1; i <= n; ++i) {
    while (top > 0 && a[stack[top]] < a[i]) {
      ans = std::max(ans, a[stack[top]] ^ a[i]);
      --top;
    }
    stack[++top] = i;
  }
  top = 0;
  for (int i = n; i >= 1; --i) {
    while (top > 0 && a[stack[top]] < a[i]) {
      ans = std::max(ans, a[stack[top]] ^ a[i]);
      --top;
    }
    stack[++top] = i;
  }
  printf("%d\n", ans);
  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>
const int MAXN = 1e5;
int n, ans, top;
int a[MAXN | 1], stack[MAXN | 1];
inline int read() {
  register int x = 0;
  register char ch = getchar();
  while (!isdigit(ch)) ch = getchar();
  while (isdigit(ch)) {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x;
}
int main() {
  n = read();
  for (int i = 1; i <= n; ++i) a[i] = read();
  for (int i = 1; i <= n; ++i) {
    while (top > 0 && a[stack[top]] < a[i]) {
      ans = std::max(ans, a[stack[top]] ^ a[i]);
      --top;
    }
    stack[++top] = i;
  }
  top = 0;
  for (int i = n; i >= 1; --i) {
    while (top > 0 && a[stack[top]] < a[i]) {
      ans = std::max(ans, a[stack[top]] ^ a[i]);
      --top;
    }
    stack[++top] = i;
  }
  printf("%d\n", ans);
  return 0;
}

```