using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace NumberConversions

{

    class NumericConversions

    {

        public int covertMe(string RomanNumeral)

        {

            string currentRomanNotation = "";

            int stringPlace = 0;

            int returnValue = 0;

            int notationValue = 0;

            int secondLetterValue = 0;

            int consecutiveCount = 0;

            char thisChar, lastChar;

            SortedDictionary<char, int> dyRoman = new SortedDictionary<char, int>{{'M', 1000}, {'D', 500}, {'C', 100}, {'L', 50}, {'X', 10}, {'V', 5}, {'I', 1}, {' ', 0}};

            try

            {

                RomanNumeral = RomanNumeral.ToUpper().TrimEnd(' ').TrimStart(' ');

                if (RomanNumeral.Contains(" "))

                    throw new ArgumentOutOfRangeException("Please enter a single Roman numeral - no spaces.", new Exception());

                for (int x = 0; x < RomanNumeral.Length; x++)

                {

                    thisChar = RomanNumeral[x];

                    lastChar = x > 0 ? RomanNumeral[x - 1] : ' ';

                    consecutiveCount = (thisChar == lastChar) ? consecutiveCount + 1 : 1;

                    if (dyRoman.TryGetValue(thisChar, out notationValue) && dyRoman.TryGetValue(lastChar, out secondLetterValue))

                    {

                        int subNumber = (notationValue.ToString()[0] == '1') ? (notationValue / 10) : (notationValue / 5);

                        if (consecutiveCount > 1 && notationValue.ToString()[0] == '5')

                            throw new ArgumentOutOfRangeException("Invalid Roman numeral - invalid letter repetitions.", new Exception());

                        if (consecutiveCount > 3)

                            throw new ArgumentOutOfRangeException("Invalid Roman numeral - specific characters cannot appear in groups of more than three.", new Exception());

                        if (subNumber > 0 && secondLetterValue > 0 && secondLetterValue != subNumber && secondLetterValue < notationValue)

                            throw new ArgumentOutOfRangeException("Invalid Roman numeral - possible error in subtractive combinations.", new Exception());

                    }

                    else

                    {

                        throw new Exception("Invalid character found.");

                    }

                }

​

                while (stringPlace < RomanNumeral.Length)

                {

                    currentRomanNotation = RomanNumeral.Substring(stringPlace, 1);

                    stringPlace++;

                    if (dyRoman.TryGetValue(currentRomanNotation[0], out notationValue))

                    {

                        if ((stringPlace <= (RomanNumeral.Length - 1)) && dyRoman.TryGetValue(RomanNumeral[stringPlace], out secondLetterValue))

                        {

                            if (secondLetterValue > notationValue)

                            {

                                currentRomanNotation += RomanNumeral[stringPlace];

                                stringPlace++;

                                notationValue = secondLetterValue - notationValue;

                            }

                        }

​

                        returnValue += notationValue;

                    }

                }

            }

            catch (Exception ex)

            {

                returnValue = 0;

                throw ex;

            }

​

            return returnValue;

        }

    }

​

    class RomanToarabic : NumericConversions

    {

    }

​

    public class Prog

    {

        public static void Main(String[] Args)

        {

            Console.WriteLine("Enter the roman numeral: ");

            string str = Console.ReadLine();

            NumericConversions conversion = new RomanToarabic();

            int arabic = conversion.covertMe(str);

            Console.WriteLine("In arabic " + arabic);

        }

    }

}