using System;

​

public class MyProgram

{

    public static void Main(String[] args)

    {

        int n;

        String str;

        str = " ";

        Console.WriteLine("Enter a number between 0 and 99:");

        input(out n);

        if (-1 < n && n < 100)

        {

            if (n == 0)

            {

                Console.WriteLine("zero");

            }

            else

            {

                while (n != 2000)

                {

                    if (n == 0)

                    {

                        str = str + " ";

                        n = 2000;

                    }

                    else

                    {

                        if (n == 1)

                        {

                            str = str + "one";

                            n = 2000;

                        }

                        else

                        {

                            if (n == 2)

                            {

                                str = str + "two";

                                n = 2000;

                            }

                            else

                            {

                                if (n == 3)

                                {

                                    str = str + "three";

                                    n = 2000;

                                }

                                else

                                {

                                    if (n == 4)

                                    {

                                        str = str + "four";

                                        n = 2000;

                                    }

                                    else

                                    {

                                        if (n == 5)

                                        {

                                            str = str + "five";

                                            n = 2000;

                                        }

                                        else

                                        {

                                            if (n == 6)

                                            {

                                                str = str + "six";

                                                n = 2000;

                                            }

                                            else

                                            {

                                                if (n == 7)

                                                {

                                                    str = str + "seven";

                                                    n = 2000;

                                                }

                                                else

                                                {

                                                    if (n == 8)

                                                    {

                                                        str = str + "eight";

                                                        n = 2000;

                                                    }

                                                    else

                                                    {

                                                        if (n == 9)

                                                        {

                                                            str = str + "nine";

                                                            n = 2000;

                                                        }

                                                        else

                                                        {

                                                            if (n == 10)

                                                            {

                                                                str = str + "ten";

                                                                n = 2000;

                                                            }

                                                            else

                                                            {

                                                                if (n == 11)

                                                                {

                                                                    str = str + "eleven";

                                                                    n = 2000;

                                                                }

                                                                else

                                                                {

                                                                    if (n == 12)

                                                                    {

                                                                        str = str + "twelve";

                                                                        n = 2000;

                                                                    }

                                                                    else

                                                                    {

                                                                        if (n == 13)

                                                                        {

                                                                            str = str + "thirteen";

                                                                            n = 2000;

                                                                        }

                                                                        else

                                                                        {

                                                                            if (n == 14)

                                                                            {

                                                                                str = str + "fourteen";

                                                                                n = 2000;

                                                                            }

                                                                            else

                                                                            {

                                                                                if (n == 15)

                                                                                {

                                                                                    str = str + "fifteen";

                                                                                    n = 2000;

                                                                                }

                                                                                else

                                                                                {

                                                                                    if (n == 16)

                                                                                    {

                                                                                        str = str + "sixteen";

                                                                                        n = 2000;

                                                                                    }

                                                                                    else

                                                                                    {

                                                                                        if (n == 17)

                                                                                        {

                                                                                            str = str + "seventeen";

                                                                                            n = 2000;

                                                                                        }

                                                                                        else

                                                                                        {

                                                                                            if (n == 18)

                                                                                            {

                                                                                                str = str + "eighteen";

                                                                                                n = 2000;

                                                                                            }

                                                                                            else

                                                                                            {

                                                                                                if (n == 19)

                                                                                                {

                                                                                                    str = str + "nineteen";

                                                                                                    n = 2000;

                                                                                                }

                                                                                                else

                                                                                                {

                                                                                                    if (n >= 20 && n < 30)

                                                                                                    {

                                                                                                        str = str + "twenty ";

                                                                                                        n = n - 20;

                                                                                                    }

                                                                                                    else

                                                                                                    {

                                                                                                        if (n >= 30 && n < 40)

                                                                                                        {

                                                                                                            str = str + "thirty ";

                                                                                                            n = n - 30;

                                                                                                        }

                                                                                                        else

                                                                                                        {

                                                                                                            if (n >= 40 && n < 50)

                                                                                                            {

                                                                                                                str = str + "fourty ";

                                                                                                                n = n - 40;

                                                                                                            }

                                                                                                            else

                                                                                                            {

                                                                                                                if (n >= 50 && n < 60)

                                                                                                                {

                                                                                                                    str = str + "fifty ";

                                                                                                                    n = n - 50;

                                                                                                                }

                                                                                                                else

                                                                                                                {

                                                                                                                    if (n >= 60 && n < 70)

                                                                                                                    {

                                                                                                                        str = str + "sixty ";

                                                                                                                        n = n - 60;

                                                                                                                    }

                                                                                                                    else

                                                                                                                    {

                                                                                                                        if (n >= 70 && n < 80)

                                                                                                                        {

                                                                                                                            str = str + "seventy ";

                                                                                                                            n = n - 70;

                                                                                                                        }

                                                                                                                        else

                                                                                                                        {

                                                                                                                            if (n >= 80 && n < 90)

                                                                                                                            {

                                                                                                                                str = str + "eighty ";

                                                                                                                                n = n - 80;

                                                                                                                            }

                                                                                                                            else

                                                                                                                            {

                                                                                                                                if (n >= 99 && n < 100)

                                                                                                                                {

                                                                                                                                    str = str + "ninety ";

                                                                                                                                    n = n - 90;

                                                                                                                                }

                                                                                                                            }

                                                                                                                        }

                                                                                                                    }

                                                                                                                }

                                                                                                            }

                                                                                                        }

                                                                                                    }

                                                                                                }

                                                                                            }

                                                                                        }

                                                                                    }

                                                                                }

                                                                            }

                                                                        }

                                                                    }

                                                                }

                                                            }

                                                        }

                                                    }

                                                }

                                            }

                                        }

                                    }

                                }

                            }

                        }

                    }

                }

                Console.WriteLine("The number you entered was" + str);

            }

        }

        else

        {

            Console.WriteLine("This is not a number between 0 and 99");

        }

    }

    // .NET can only read single characters or entire lines from the console.

    // The following functions are designed to help input specific data types.

    private static void input(out double result)

    {

        while (!double.TryParse(Console.ReadLine(), out result));

    }

    private static void input(out int result)

    {

        while (!int.TryParse(Console.ReadLine(), out result));

    }

    private static void input(out Boolean result)

    {

        while (!Boolean.TryParse(Console.ReadLine(), out result));

    }

    private static void input(out string result)

    {

        result = Console.ReadLine();

    }

}

​