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.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.util.Stack;

public class CFFF {
	static PrintWriter out;
	public static void main(String[] args) {
		MScanner sc = new MScanner();
		out = new PrintWriter(System.out);		
		
		int N = sc.nextInt();
		int[] array = sc.nextInt(N);
		int best = 0;
		Stack<Integer> s = new Stack<Integer>();
		
		for(int a=0;a<N;a++){
			while(!s.isEmpty()){
				best = Math.max(best,s.peek()^array[a]);
				if(s.peek()<array[a])s.pop();
				else break;
			}
			s.add(array[a]);
		}
		
		out.println(best); 
		out.close();
	}
	

	static class MScanner {
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public MScanner() {
			stream = System.in;
			// stream = new FileInputStream(new File("dec.in"));

		}

		int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		boolean isEndline(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

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

		int[] nextInt(int N) {
			int[] ret = new int[N];
			for (int a = 0; a < N; a++)
				ret[a] = nextInt();
			return ret;
		}

		int[][] nextInt(int N, int M) {
			int[][] ret = new int[N][M];
			for (int a = 0; a < N; a++)
				ret[a] = nextInt(M);
			return ret;
		}

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

		long[] nextLong(int N) {
			long[] ret = new long[N];
			for (int a = 0; a < N; a++)
				ret[a] = nextLong();
			return ret;
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		double[] nextDouble(int N) {
			double[] ret = new double[N];
			for (int a = 0; a < N; a++)
				ret[a] = nextDouble();
			return ret;
		}

		String next() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		String[] next(int N) {
			String[] ret = new String[N];
			for (int a = 0; a < N; a++)
				ret[a] = next();
			return ret;
		}

		String nextLine() {
			int c = read();
			while (isEndline(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndline(c));
			return res.toString();
		}

		String[] nextLine(int N) {
			String[] ret = new String[N];
			for (int a = 0; a < N; a++)
				ret[a] = nextLine();
			return ret;
		}

	}
}
