Конвертор за мерни единици

using System;

namespace tESt
{
    class Program
    {
        static void Main(string[] args)
        {

            double length = double.Parse(Console.ReadLine());

            string firstType = Console.ReadLine();
            string secondType = Console.ReadLine();

            const double mm = 1000;
            const double cm = 100;
            const double mi = 0.000621371192;
            const double inch = 39.3700787;
            const double km = 0.001;
            const double ft = 3.2808399;
            const double yd = 1.0936133;


            if (firstType == "mm")
            {
                length /= mm;
            }
            if (firstType == "cm")
            {
                length /= cm;
            }
            else if (firstType == "mi")
            {
                length /= mi;
            }
            else if (firstType == "in")
            {
                length /= inch;
            }
            else if (firstType == "km")
            {
                length /= km;
            }
            else if (firstType == "ft")
            {
                length /= ft;
            }
            else if (firstType == "yd")
            {
                length /= yd;
            }




            if (secondType == "cm")
            {
                length *= cm;
            }
            else if (secondType == "mi")
            {
                length *= mi;
            }
            else if (secondType == "in")
            {
                length *= inch;
            }
            else if (secondType == "km")
            {
                length *= km;
            }
            else if (secondType == "ft")
            {
                length *= ft;
            }
            else if (secondType == "yd")
            {
                length *= yd;
            }
            else if (secondType == "mm")
            {
                length *= mm;
            }


            Console.WriteLine(length);


        }
    }
}