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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        boolean[] enable = new boolean[4000001];
        int size = 0;
        enable[0] = true;
        for (int i = 0; i < n; i++) {
            int x = sc.nextInt();
            size += x;
            for (int j = size; j - x >= 0; j--) {
                enable[j] ^= enable[j - x];
            }
        }
        int ans = 0;
        for (int i = 0; i <= size; i++) {
            if (enable[i]) {
                ans ^= i;
            }
        }
        System.out.println(ans);
    }
    
}
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 double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}