using System;
using System.Linq;

namespace ConsoleApplication2
{
	class Program
	{
		static void Main(string[] args)
		{
			var mask = Enumerable.Range(0, 31).Select(x => 1 << x).Reverse().ToArray();
			Console.ReadLine();

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



			foreach (var m in mask)
			{
				var currentMax = current.Max();
				candidate = current.Select(x => x ^ m).ToArray();
				var candidateMax = candidate.Max();

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

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