using System;

public class Program

{

    public static void Main()

    {

        while(true)

        {

        Console.WriteLine("Would you like: Hex to Denary(HD) or Denary to Hex(DH)");

        string AnswerTo = Console.ReadLine();

        if(AnswerTo == "DH")

        {

        int i = 0;

        Console.WriteLine("Please enter a number");

        int denaryNum = Convert.ToInt32(Console.ReadLine());

        int value = denaryNum;

        string binaryNum = Convert.ToString(value, 2);

        string [] arrayNum = new string [binaryNum.Length];

        for(i = 0; i < binaryNum.Length; i++)

        {

               arrayNum[i] = binaryNum.Substring(i, 1);

        }

        for(i = 0; i < binaryNum.Length; i++) 

        {

            if((i+1)%4 == 0)

            {   

                string x = arrayNum[i-3] + arrayNum[i-2] + arrayNum[i-1] + arrayNum[i];     

                if (x == "0000")

                {

                    Console.Write(0);

                }

                if (x == "0001")

                {

                    Console.Write(1);

                }

                if (x == "0010")

                {

                    Console.Write(2);

                }

                if (x == "0011")

                {

                    Console.Write(3);

                }

                if (x == "0100")

                {

                    Console.Write(4);

                }

                if (x == "0101")

                {

                    Console.Write(5);

                }

                if (x == "0110")

                {

                    Console.Write(6);

                }

                if (x == "0111")

                {

                    Console.Write(7);

                }

                if (x == "1000")

                {

                    Console.Write(8);

                }

                if (x == "1001")

                {

                    Console.Write(9);

                }

                if (x == "1010")

                {

                    Console.Write("A");

                }

                if (x == "1011")

                {

                    Console.Write("B");

                }

                if (x == "1100")

                {

                    Console.Write("C");

                }

                if (x == "1101")

                {

                    Console.Write("D");

                }

                if (x == "1110")

                {

                    Console.Write("E");

                }

                if (x == "1111")

                {

                    Console.Write("F");

                }   

              }

              Console.WriteLine();

              if (AnswerTo == "HD")

              {

                  Console.WriteLine("Enter a Hex Number");

                  string hexNumber = Console.ReadLine();

                  string [] arrayNumber = new string [hexNumber.Length];

                  for(i = 0; i < hexNumber.Length; i++)                     

              {

               arrayNumber[i] = hexNumber.Substring(i, 1); 

              }

                for(i = 0; i < arrayNumber.Length; i++)

                {

                   if (arrayNumber[i] == "0000")

                   {

                       Console.Write(0000);

                   }

                   if (arrayNumber[i] == "1")

                   { 

                       Console.Write(0001);

                   }

                   if (arrayNumber[i] == "2")

                   {

                       Console.Write(0010);

                   }

                   if (arrayNumber[i] == "3")

                   {

                       Console.Write(0011);

                   }

                   if (arrayNumber[i] == "4")

                   {

                       Console.Write(0100);

                   }

                   if (arrayNumber[i] == "5")

                   {

                       Console.Write(0101);

                   }

                   if (arrayNumber[i] == "6")

                   {

                      Console.Write(0110);

                   }

                   if (arrayNumber[i] == "7")

                   {

                       Console.Write(0111);

                   }

                   if (arrayNumber[i] == "8")

                   {

                       Console.Write(1000);

                   }

                   if (arrayNumber[i] == "9")

                   {

                       Console.Write(1001);

                   }

                   if (arrayNumber[i] == "A")

                   {

                       Console.Write(1010);

                   }

                   if (arrayNumber[i] == "B")

                   {

                       Console.Write(1011);

                   }

                   if (arrayNumber[i] == "C")

                   {

                       Console.Write(1100);

                   }

                   if (arrayNumber[i] == "D")

                   {

                       Console.Write(1101);

                   }

                   if (arrayNumber[i] == "E")

                   {

                       Console.Write(1110);

                   }

                   if (arrayNumber[i] == "F")

                   {

                       Console.Write(1111);

                   }

                   string LargeHex = arrayNumber[i] + arrayNumber[i+1];

                   Console.WriteLine(LargeHex); 

                }

              Console.WriteLine("would you like to continue");

                string answer = Console.ReadLine();

                if (answer == "no")

                {

                    break;

                }

            }               

         }      

      }

   }        

  } 

}