import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

/*
2
3 5

3
4 9 13

3
2 9 32

 */
public class Shopping {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        List<Long> nums = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            nums.add(in.nextLong());
        }

        long solution = 0;
        long allBits = 0;
        for(long bit = 1; bit<=4000000000000000000L; bit<<=1) {
            boolean isPresent = false;
            long sum = 0;
            for(long num : nums) {
                if((num & bit) > 0) {
                    isPresent = true;
                    break;
                }
                sum += num & allBits;
            }
            if((sum & bit) > 0) {
                isPresent = true;
            }
            if(isPresent) {
                solution |= bit;
            }
            allBits |= bit;
        }
        System.out.println(solution);
    }
}