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.*;
import java.util.*;

public class CF {
	FastScanner in;
	PrintWriter out;

	void solve() {
		int n = in.nextInt();
		int[] a = new int[n];
		int res = 0;
		for (int i = 0; i < n; i++)
			a[i] = in.nextInt();
		ArrayList<Integer> cur = new ArrayList<>();
		int[] nextBiggerRight = new int[n];
		Arrays.fill(nextBiggerRight, -1);
		for (int i = 0; i < n; i++) {
			int val = a[i];
			while (cur.size() > 0 && a[cur.get(cur.size() - 1)] < val) {
				int tmp = cur.get(cur.size() - 1);
				nextBiggerRight[tmp] = i;
				cur.remove(cur.size() - 1);
			}
			cur.add(i);
		}
		
		cur = new ArrayList<>();
		int[] nextBiggerLeft = new int[n];
		Arrays.fill(nextBiggerLeft, -1);
		for (int i = n - 1; i >= 0; i--) {
			int val = a[i];
			while (cur.size() > 0 && a[cur.get(cur.size() - 1)] < val) {
				int tmp = cur.get(cur.size() - 1);
				nextBiggerLeft[tmp] = i;
				cur.remove(cur.size() - 1);
			}
			cur.add(i);
		}
		for (int maxPos = 0; maxPos < n; maxPos++) {
			int it1 = maxPos + 1;
			while (it1 != -1 && it1 < n && a[it1] < a[maxPos]) {
				res = Math.max(res, a[maxPos] ^ a[it1]);
				it1 = nextBiggerRight[it1];
			}
			int it2 = maxPos - 1;
			while (it2 != -1 && a[it2] < a[maxPos]) {
				res = Math.max(res, a[maxPos] ^ a[it2]);
				it2 = nextBiggerLeft[it2];
			}
		}
		out.println(res);
	}

	void run() {
		try {
			in = new FastScanner(new File("test.in"));
			out = new PrintWriter(new File("test.out"));

			solve();

			out.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}

	void runIO() {

		in = new FastScanner(System.in);
		out = new PrintWriter(System.out);

		solve();

		out.close();
	}

	class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner(File f) {
			try {
				br = new BufferedReader(new FileReader(f));
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			}
		}

		public FastScanner(InputStream f) {
			br = new BufferedReader(new InputStreamReader(f));
		}

		String next() {
			while (st == null || !st.hasMoreTokens()) {
				String s = null;
				try {
					s = br.readLine();
				} catch (IOException e) {
					e.printStackTrace();
				}
				if (s == null)
					return null;
				st = new StringTokenizer(s);
			}
			return st.nextToken();
		}

		boolean hasMoreTokens() {
			while (st == null || !st.hasMoreTokens()) {
				String s = null;
				try {
					s = br.readLine();
				} catch (IOException e) {
					e.printStackTrace();
				}
				if (s == null)
					return false;
				st = new StringTokenizer(s);
			}
			return true;
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}
	}

	public static void main(String[] args) {
		new CF().runIO();
	}
}