//Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.

​

using System;

public class Program

{

    public static int Convert(char c)

    {

        switch(c)

        {

            case 'I':

            return 1;

            case 'V':

            return 5;

            case 'X':

            return 10;

            case 'L':

            return 50;

            case 'C':

            return 100;

            case 'D':

            return 500;

            case 'M':

            return 1000;

            default:

            return 0;

        }

    }

    public static int RomanToInt(string s) {

        char[] chars = s.ToCharArray();

        int result = 0;

        for(int i=0; i<chars.Length-1; i++)

        {

            if(Convert(chars[i]) >= Convert(chars[i+1]))

            {

                result += Convert(chars[i]);

                Console.WriteLine("Result + " + result);

            }

            else 

            {

                result -= Convert(chars[i]);    

                Console.WriteLine("Result - " + result);

            }

        }

        result+=Convert(chars[chars.Length-1]);

       return result;

    }

    public static void Main()

    {

        // DCXXI - 621

        Console.WriteLine(RomanToInt("DCXXI"));

    }

}