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(); ArrayList list = new ArrayList<>(); for (int i = 0; i < n; i++) { list.add(sc.nextInt()); } System.out.println(dfw(30, list)); } static int dfw(int idx, ArrayList list) { if (idx < 0) { return 0; } ArrayList ev = new ArrayList<>(); ArrayList od = new ArrayList<>(); for (int x : list) { if ((x & (1 << idx)) == 0) { ev.add(x); } else { od.add(x); } } if (ev.size() == 0) { return dfw(idx - 1, od); } else if (od.size() == 0) { return dfw(idx - 1, ev); } else { return Math.min(dfw(idx - 1, od), dfw(idx - 1, ev)) + (1 << idx); } } } 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(); } }