#include <bits/stdc++.h>
using namespace std;
template <class T1>
void deb(T1 e) {
  cout << e << endl;
}
template <class T1, class T2>
void deb(T1 e1, T2 e2) {
  cout << e1 << " " << e2 << endl;
}
template <class T1, class T2, class T3>
void deb(T1 e1, T2 e2, T3 e3) {
  cout << e1 << " " << e2 << " " << e3 << endl;
}
template <class T1, class T2, class T3, class T4>
void deb(T1 e1, T2 e2, T3 e3, T4 e4) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << endl;
}
template <class T1, class T2, class T3, class T4, class T5>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << endl;
}
template <class T1, class T2, class T3, class T4, class T5, class T6>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5, T6 e6) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << " " << e6
       << endl;
}
long long sqr(long long n) { return n * n; }
double LOG(long long a, long long b) { return (log(a) / log(b)); }
long long GCD(long long a, long long b) {
  if (a < 0) return GCD(-a, b);
  if (b < 0) return GCD(a, -b);
  return (!b) ? a : GCD(b, a % b);
}
long long LCM(long long a, long long b) {
  if (a < 0) return LCM(-a, b);
  if (b < 0) return LCM(a, -b);
  return (a * (b / GCD(a, b)));
}
long long BigMod(long long B, long long P, long long M) {
  if (!P) return 1;
  if (!(P % 2)) return sqr(BigMod(B, P / 2, M)) % M;
  return (B % M) * (BigMod(B, P - 1, M)) % M;
}
vector<long long> nums;
long long st[100000 + 5];
int main(void) {
  long long i, n, x;
  cin >> n;
  nums.clear();
  for (i = 0; i < n; i++) {
    scanf("%I64d", &x);
    nums.push_back(x);
  }
  long long cur = 0ll;
  st[cur++] = nums[0];
  long long res = 0ll;
  for (i = 1; i < n; i++) {
    if (cur && nums[i] < st[cur - 1]) {
      res = max(res, nums[i] ^ st[cur - 1]);
      st[cur++] = nums[i];
    } else {
      while (cur && nums[i] > st[cur - 1]) {
        res = max(res, nums[i] ^ st[cur - 1]);
        cur--;
      }
      if (cur) res = max(res, nums[i] ^ st[cur - 1]);
      st[cur++] = nums[i];
    }
  }
  deb(res);
  return 0;
}

### Prompt

In cpp, your task is to solve 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;
template <class T1>
void deb(T1 e) {
  cout << e << endl;
}
template <class T1, class T2>
void deb(T1 e1, T2 e2) {
  cout << e1 << " " << e2 << endl;
}
template <class T1, class T2, class T3>
void deb(T1 e1, T2 e2, T3 e3) {
  cout << e1 << " " << e2 << " " << e3 << endl;
}
template <class T1, class T2, class T3, class T4>
void deb(T1 e1, T2 e2, T3 e3, T4 e4) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << endl;
}
template <class T1, class T2, class T3, class T4, class T5>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << endl;
}
template <class T1, class T2, class T3, class T4, class T5, class T6>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5, T6 e6) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << " " << e6
       << endl;
}
long long sqr(long long n) { return n * n; }
double LOG(long long a, long long b) { return (log(a) / log(b)); }
long long GCD(long long a, long long b) {
  if (a < 0) return GCD(-a, b);
  if (b < 0) return GCD(a, -b);
  return (!b) ? a : GCD(b, a % b);
}
long long LCM(long long a, long long b) {
  if (a < 0) return LCM(-a, b);
  if (b < 0) return LCM(a, -b);
  return (a * (b / GCD(a, b)));
}
long long BigMod(long long B, long long P, long long M) {
  if (!P) return 1;
  if (!(P % 2)) return sqr(BigMod(B, P / 2, M)) % M;
  return (B % M) * (BigMod(B, P - 1, M)) % M;
}
vector<long long> nums;
long long st[100000 + 5];
int main(void) {
  long long i, n, x;
  cin >> n;
  nums.clear();
  for (i = 0; i < n; i++) {
    scanf("%I64d", &x);
    nums.push_back(x);
  }
  long long cur = 0ll;
  st[cur++] = nums[0];
  long long res = 0ll;
  for (i = 1; i < n; i++) {
    if (cur && nums[i] < st[cur - 1]) {
      res = max(res, nums[i] ^ st[cur - 1]);
      st[cur++] = nums[i];
    } else {
      while (cur && nums[i] > st[cur - 1]) {
        res = max(res, nums[i] ^ st[cur - 1]);
        cur--;
      }
      if (cur) res = max(res, nums[i] ^ st[cur - 1]);
      st[cur++] = nums[i];
    }
  }
  deb(res);
  return 0;
}

```