using System;

​

public class Program

{

    public static void Main()

    {

        string yearsVar;

        double yearsNum, convertNum;

        Console.WriteLine("Enter \"human to dog years\" or \"dog to human years\"");

        yearsVar = Console.ReadLine();

        if (yearsVar == "human to dog years")

        {

            Console.WriteLine("Enter number of years");

            yearsNum = Convert.ToDouble(Console.ReadLine());

            if (yearsNum >= 0 && yearsNum < 2)

            {

                convertNum = yearsNum * 15;

                Console.WriteLine(convertNum);

            }

​

            if (yearsNum >= 2 && yearsNum < 3)

            {

                convertNum = 9 * (yearsNum - 1) + 15;

                Console.WriteLine(convertNum);

            }

​

            if (yearsNum >= 3)

            {

                convertNum = 5 * (yearsNum - 2) + 24;

                Console.WriteLine(convertNum);

            }

            else

                Console.WriteLine("Invalid input");

            ;

        }

​

        if (yearsVar == "dog to human years")

        {

            Console.WriteLine("Enter number of years");

            yearsNum = Convert.ToDouble(Console.ReadLine());

            if (yearsNum > 0 && yearsNum < 15)

            {

                convertNum = yearsNum / 15;

                Console.WriteLine(convertNum);

            }

​

            if (yearsNum >= 15 && yearsNum < 24)

            {

                convertNum = (yearsNum - 15) / 9 + 1;

                Console.WriteLine(convertNum);

            }

​

            if (yearsNum >= 24)

            {

                convertNum = (yearsNum - 24) / 5 + 2;

                Console.WriteLine(convertNum);

            }

            else

                Console.WriteLine("Invalid input");

        }

​

        ;

    }

}