import java.util.*;

public class Main {
    static int n;
    static int[] arr;
    static int max = Integer.MIN_VALUE;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        arr = new int[n];
        for (int i = 0; i < n; i++ ){
            arr[i] = sc.nextInt();
        }
        search(1, new int[n]);
        System.out.println(max);
    }
    
    static void search(int count, int[] used) {
        if (count > n / 2) {
            int[] base = new int[n / 2 + 1];
            for (int i = 0; i < n; i++) {
                base[used[i]] += arr[i];
            }
            int ans = 0;
            for (int i = 1; i < base.length; i++) {
                ans ^= base[i];
            }
            max = Math.max(ans, max);
            return;
        }
        for (int i = 0; i < count * 2 - 1; i++) {
            if (used[i] != 0) {
                continue;
            }
            used[i] = count;
            for (int j = i + 1; j < n; j++) {
                if (used[j] != 0) {
                    continue;
                }
                used[j] = count;
                search(count + 1, used);
                used[j] = 0;
            }
            used[i] = 0;
        }
    }
}