import java.util.*;

public class Main {
    static int[] base;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        base = new int[31];
        base[0] = 1;
        for (int i = 1; i < base.length; i++) { 
            base[i] = base[i - 1] * 2;
        }
        HashSet<Integer> set = new HashSet<>();
        for (int i = 0; i < n; i++) {
            set.add(sc.nextInt());
        }
        System.out.println(getMin(30, set));
    }
    
    static int getMin(int idx, HashSet<Integer> set) {
        if (idx == 0) {
            if(set.size() == 1) {
                return 0;
            } else {
                return 1;
            }
        }
        HashSet<Integer> next = new HashSet<>();
        for (int x : set) {
            if (x >= base[idx]) {
                next.add(x);
            }
        }
        if (next.size() == 0) {
            return getMin(idx - 1, set);
        } else if (next.size() == set.size()) {
            HashSet<Integer> tmp = new HashSet<>();
            for (int x : next) {
                tmp.add(x - base[idx]);
            }
            return getMin(idx - 1, tmp);
        } else {
            HashSet<Integer> tmp = new HashSet<>();
            for (int x : next) {
                tmp.add(x - base[idx]);
                set.remove(x);
            }
            return base[idx] + Math.min(getMin(idx - 1, set), getMin(idx - 1, tmp));
        }
    }
}