using System;

using System.Text;

using System.Linq;

public class Program

{

    private static readonly UnicodeEncoding bigEndianUnicode = new UnicodeEncoding(true, true);

    public static string HexEncode(string stringValue)

    {

      var ba = bigEndianUnicode.GetBytes(stringValue);

      var hex = new StringBuilder(ba.Length * 2);

      foreach (var b in ba)

        hex.AppendFormat("{0:x2}", b);

      return hex.ToString();

    }

    public static string HexDecode(string hexString)

    {

      if (hexString == null || (hexString.Length & 1) == 1) return "";

      var numberChars = hexString.Length;

      var bytes = new byte[numberChars / 2];

      for (var i = 0; i < numberChars; i += 2)

        bytes[i / 2] = Convert.ToByte(hexString.Substring(i, 2), 16);

      return bigEndianUnicode.GetString(bytes);

    }

    public static void Main()

    {

        var hex = HexEncode("그러하지");

        var str = HexDecode(hex);

        Console.WriteLine("Encoded: {0}", string.Join(",", hex));

        Console.WriteLine("Decoded: {0}", str);

    }

}