package yukicoder;

import java.util.*;

public class Q130 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long[] a = new long[n];
		for (int i = 0; i < n; ++i) {
			a[i] = sc.nextLong();
		}
		Arrays.sort(a);
		/*
		 * long ans = 0; for (int t = 0; t < 100; ++t) { for (long i = 32; i >=
		 * 0; --i) {// 3=1,1, if ((a[n - 1] & (1L << i)) > 0) { long[] tmp =
		 * Arrays.copyOf(a, n); long tmpMax = 0; for (int j = 0; j < n; ++j) {
		 * tmp[j] = a[j] ^ (1L << i); tmpMax = Math.max(tmpMax, tmp[j]); } if
		 * (tmpMax < a[n - 1]) { if ((ans & (1L << i)) > 0) throw new
		 * AssertionError(); ans |= 1L << i; a = tmp; Arrays.sort(a); break; } }
		 * } }
		 */
		System.out.println(dfs(a, 0));
		// System.out.println(a[n - 1]);
	}

	// Suppose that a is sorted
	static long dfs(long[] a, long p) {
		int n = a.length;
		long min = a[n - 1];
		boolean f = true;
		while (f) {
			long dumy = a[n - 1];
			outer:for (long i = 32; i >= 0; --i) {// 3=1,1,
				if ((a[n - 1] & (1L << i)) > 0 && ((p & (1L << i)) == 0)) {
					long[] tmp = Arrays.copyOf(a, n);
					long tmpMax = 0;
					for (int j = 0; j < n; ++j) {
						tmp[j] = a[j] ^ (1L << i);
						tmpMax = Math.max(tmpMax, tmp[j]);
					}
					if (tmpMax < a[n - 1]) {
						if ((p & (1L << i)) > 0)
							throw new AssertionError();
						p |= 1L << i;
						a = tmp;
						Arrays.sort(a);
						break outer;
					} else if (tmpMax == a[n - 1]) {
						long[] next = Arrays.copyOf(tmp, n);
						Arrays.sort(next);
						min = Math.min(dfs(next, p | (1L << i)), min);
					}
				}
			}
			if (dumy == a[n - 1])
				f = false;
		}
		return Math.min(min, a[n - 1]);
	}
}