import java.util.*;
import java.io.*;
import java.math.*;
// import java.util.stream.Stream;

class Main{
    static BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st;
    static PrintWriter output = new PrintWriter(System.out);
    static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) throws IOException{
        int n = sc.nextInt();
        long [] A = new long[n];
        long OR = 0L;
        long answer = (long)1e18+1;
        for(int i=0;i<n;i++) A[i] = sc.nextLong();
        for(int i=0;i<n;i++) OR |= A[i];
        for(int i=0;i<=60;i++) {
            long bit = (OR>>i) & 1;
            if(bit == 0) {
                output.println((1L<<i));
                break;
            }
        }
        output.flush();
    }
}