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}.
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;


public class cf280b {
  public static void main(String[] args) {
    FastIO in = new FastIO(), out = in;
    int n = in.nextInt();
    int[] stk = new int[n+1];
    int[] v = new int[n];
    for(int i=0; i<n; i++) v[i] = in.nextInt();
    int cur = 0;
    int ans = 0;
    while(cur < n) {
      if(stk[0] > 0 && cur < n) {
        ans = Math.max(ans, stk[stk[0]]^v[cur]);
      }
      if(stk[0] > 0 && v[cur] > stk[stk[0]]) {
        stk[0]--;
      }
      else {
        stk[++stk[0]] = v[cur++];
      }
    }
    out.println(ans);
    out.close();
  }
  static class FastIO extends PrintWriter {
    BufferedReader br;
    StringTokenizer st;
    
    public FastIO() {
      this(System.in,System.out);
    }
    public FastIO(InputStream in, OutputStream out) {
      super(new BufferedWriter(new OutputStreamWriter(out)));
      br = new BufferedReader(new InputStreamReader(in));
      scanLine();
    }
    public void scanLine() {
      try {
        st = new StringTokenizer(br.readLine().trim());
      } catch(Exception e) {
        throw new RuntimeException(e.getMessage());
      }
    }
    public int numTokens() {
      if(!st.hasMoreTokens()) {
        scanLine();
        return numTokens();
      }
      return st.countTokens();
    }
    public String next() {
      if(!st.hasMoreTokens()) {
        scanLine();
        return next();
      }
      return st.nextToken();
    }
    public double nextDouble() {
      return Double.parseDouble(next());
    }
    public long nextLong() {
      return Long.parseLong(next());
    }
    public int nextInt() {
      return Integer.parseInt(next());
    }
  }
}
