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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        TreeSet<Integer> base = new TreeSet<>();
        for (int i = 0; i < n; i++) {
            int x = sc.nextInt();
            while (base.contains(x)) {
                base.remove(x);
                x *= 2;
            }
            base.add(x);
        }
        TreeSet<Integer> set = new TreeSet<>();
        set.add(0);
        for (int x : base) {
            Integer key = Integer.MAX_VALUE;
            while ((key = set.lower(key)) != null) {
                if (set.contains(key + x)) {
                    set.remove(key + x);
                } else {
                    set.add(key + x);
                }
            }
        }
        int ans = 0;
        for (int x : set) {
            ans ^= x;
        }
        System.out.println(ans);
    }
}

class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}