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; } } }