using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;


namespace ConsoleApplication2
{
	class Program
	{
		static void Main(string[] args)
		{
#if LOCAL
			Console.SetIn(new StreamReader("test04.txt"));
#endif
			var mask = Enumerable.Range(0, 32).Select(x => (uint)1 << x).Reverse().ToArray();
			Console.ReadLine();

			var current = Console.ReadLine().Split().Select(x => uint.Parse(x)).ToArray();
			uint[] candidate = new uint[0];



			foreach (var m in mask.Reverse())
			{


				var currentMax = current.Max();

				candidate = current.Select(x => x ^ m).ToArray();
				var candidateMax = candidate.Max();

				if (currentMax > candidateMax)
				{
					current = candidate;
				}
			}

			Console.WriteLine(current.Max());
		}
	}
}