#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int n, ans, a[N], top, sta[N];
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 3) + (x << 1) + (ch ^ 48);
    ch = getchar();
  }
  return x * f;
}
void work() {
  top = 0;
  for (int i = 1; i <= n; i++) {
    while (top && a[sta[top]] < a[i]) top--;
    if (top) ans = max(ans, a[i] ^ a[sta[top]]);
    sta[++top] = i;
  }
}
int main() {
  n = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  work();
  reverse(a + 1, a + n + 1);
  work();
  printf("%d\n", ans);
  fclose(stdin);
  fclose(stdout);
  return 0;
}

### Prompt

Construct a cpp code solution to the problem outlined:

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 N = 1e5 + 5;
int n, ans, a[N], top, sta[N];
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 3) + (x << 1) + (ch ^ 48);
    ch = getchar();
  }
  return x * f;
}
void work() {
  top = 0;
  for (int i = 1; i <= n; i++) {
    while (top && a[sta[top]] < a[i]) top--;
    if (top) ans = max(ans, a[i] ^ a[sta[top]]);
    sta[++top] = i;
  }
}
int main() {
  n = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  work();
  reverse(a + 1, a + n + 1);
  work();
  printf("%d\n", ans);
  fclose(stdin);
  fclose(stdout);
  return 0;
}

```