namespace _6_Middle_Characters
{
    using System;
    using System.Linq;

    public class Program
    {
        public static void Main()
        {
            string letter = Console.ReadLine();

            string result = GetEvenOrOddLetterLength(letter);

            Console.WriteLine(result);
        }

        public static string GetEvenOrOddLetterLength(string letter)
        {
            if (letter.Length % 2 == 0)
            {
                return GetEvenLetterLength(letter);
            }
            else
            {
                return GetOddLetterLength(letter);
            }
        }

        public static string GetEvenLetterLength(string letter)
        {
            var s = letter.ToCharArray().Select(c => c.ToString()).ToArray();

            string[] firstArray = s.Take(s.Length / 2).ToArray();
            string[] secondArray = s.Skip(s.Length / 2).ToArray();

            string lastCharacter = firstArray.Last();
            string firstCharacter = secondArray.First();
            string result = string.Concat(lastCharacter, firstCharacter);

            return result;
        }

        public static string GetOddLetterLength(string letter)
        {
            char middle = letter[letter.Length / 2];
            string middleElement = middle.ToString();

            return middleElement;
        }
    }
}