DO YOU EXPECT ME TO FIND THIS OUT?

WHAT BASE AND/XOR LANGUAGE INCLUDES string?

DON'T BYTE OF MORE THAN YOU CAN CHEW

YOU CAN ONLY DISTORT THE LARGEST OF MATHEMATICS SO FAR

SAYING "ABRACADABRA" WITHOUT A MAGIC AND WON'T DO YOU ANY GOOD

THE LAST STACK RUPTURES. ALL DIE. OH, THE EMBARRASSMENT!

I HAVE NO ARRAY AND I MUST SCREAM

ELEMENTS MAY NOT BE STORED IN WEST HYPERSPACE

Input

The first line of input data contains a single integer n (1 ≤ n ≤ 10).

The second line of input data contains n space-separated integers ai (1 ≤ ai ≤ 11).

Output

Output a single integer.

Example

Input

4
2 5 3 1


Output

4
import java.util.Scanner;

public class c {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);

		int n = in.nextInt();
		in.nextLine();
		String line = in.nextLine();
		String[] splitLn = line.split(" ");

		int[] nums = new int[n];

		for (int i = 0; i < splitLn.length; i++) {
			nums[i] = Integer.parseInt(splitLn[i]);
		}

		int max = nums[0];
		for (int i : nums) {
			if (i > max) {
				max = i;
			}
		}

		System.out.println(max ^ nums[nums.length - 1]);

		in.close();
	}
}
