#include <bits/stdc++.h>
using namespace std;
const int N = 500001;
long long int gcd(long long int a, long long int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long int lcm(long long int a, long long int b) {
  return a * b / gcd(a, b);
}
using namespace std;
long long int max(long long int a, long long int b) {
  if (a > b) return a;
  return b;
}
long long int min(long long int a, long long int b) {
  if (a < b) return a;
  return b;
}
long long int inf = 100000000000000000;
vector<int> adj[N];
vector<int> rev[N];
long long int mod = 1000000007;
long long int mod1 = 998244353;
long long int power(long long int a, long long int b) {
  long long int res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
long long int power1(long long int a, long long int b) {
  long long int res = 1;
  a %= mod1;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod1;
    a = a * a % mod1;
  }
  return res;
}
long long int modInverse(long long int a) { return power(a, mod - 2); }
long long int modInverse1(long long int a) { return power1(a, mod1 - 2); }
void solve() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (long long int i = 0; i < n; i++) cin >> a[i];
  stack<int> st;
  long long int ans = a[0] ^ a[1];
  for (long long int i = 0; i < n; i++) {
    while (st.size() != 0 && a[i] > st.top()) {
      st.pop();
    }
    st.push(a[i]);
    if (st.size() >= 2) {
      int x = st.top();
      st.pop();
      int y = st.top();
      st.push(x);
      ans = max(ans, x ^ y);
    }
  }
  reverse((a).begin(), (a).end());
  ans = max(ans, a[0] ^ a[1]);
  for (long long int i = 0; i < n; i++) {
    while (st.size() != 0 && a[i] > st.top()) {
      st.pop();
    }
    st.push(a[i]);
    if (st.size() >= 2) {
      int x = st.top();
      st.pop();
      int y = st.top();
      st.push(x);
      ans = max(ans, x ^ y);
    }
  }
  cout << ans << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int T = 1;
  int t = 0;
  while (t++ < T) {
    solve();
  }
  cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC
       << "ms\n";
}

### Prompt

Generate 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;
const int N = 500001;
long long int gcd(long long int a, long long int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long int lcm(long long int a, long long int b) {
  return a * b / gcd(a, b);
}
using namespace std;
long long int max(long long int a, long long int b) {
  if (a > b) return a;
  return b;
}
long long int min(long long int a, long long int b) {
  if (a < b) return a;
  return b;
}
long long int inf = 100000000000000000;
vector<int> adj[N];
vector<int> rev[N];
long long int mod = 1000000007;
long long int mod1 = 998244353;
long long int power(long long int a, long long int b) {
  long long int res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
long long int power1(long long int a, long long int b) {
  long long int res = 1;
  a %= mod1;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod1;
    a = a * a % mod1;
  }
  return res;
}
long long int modInverse(long long int a) { return power(a, mod - 2); }
long long int modInverse1(long long int a) { return power1(a, mod1 - 2); }
void solve() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (long long int i = 0; i < n; i++) cin >> a[i];
  stack<int> st;
  long long int ans = a[0] ^ a[1];
  for (long long int i = 0; i < n; i++) {
    while (st.size() != 0 && a[i] > st.top()) {
      st.pop();
    }
    st.push(a[i]);
    if (st.size() >= 2) {
      int x = st.top();
      st.pop();
      int y = st.top();
      st.push(x);
      ans = max(ans, x ^ y);
    }
  }
  reverse((a).begin(), (a).end());
  ans = max(ans, a[0] ^ a[1]);
  for (long long int i = 0; i < n; i++) {
    while (st.size() != 0 && a[i] > st.top()) {
      st.pop();
    }
    st.push(a[i]);
    if (st.size() >= 2) {
      int x = st.top();
      st.pop();
      int y = st.top();
      st.push(x);
      ans = max(ans, x ^ y);
    }
  }
  cout << ans << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int T = 1;
  int t = 0;
  while (t++ < T) {
    solve();
  }
  cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC
       << "ms\n";
}

```