import java.io.*;
import java.util.*;

public class Main {
    static int n;
    static int[] values;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        n = sc.nextInt();
        values = new int[n];
        for (int i = 0; i < n; i++) {
            values[i] = sc.nextInt();
        }
        System.out.println(check1(0, new boolean[n]));
    }
    
    static int check1(int idx, boolean[] used) {
        if (idx == n) {
            return 0;
        }
        int ans = 0;
        for (int i = 0; i < n; i++) {
            if (!used[i]) {
                used[i] = true;
                ans = check2(idx + 1, used, values[i]);
                used[i] = false;
                break;
            }
        }
        return ans;
    }
    
    static int check2(int idx, boolean[] used, int v) {
        int max = 0;
        for (int i = 0; i < n; i++) {
            if (used[i]) {
                continue;
            } 
            used[i] = true;
            max = Math.max(max, (v ^ values[i]) + check1(idx + 1, used));
            used[i] = false;
        }
        return max;
    }
    
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public String nextLine() throws Exception {
        return br.readLine();
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}