using System;

​

namespace FlipACoin

{

    public class Program

    {

        public static void Main()

        {

            //declare variables

            string guessString;

            string headsOrTails;

            byte guess;

            byte result;

            bool validNumber;

            //ask user for input

            Console.WriteLine("Heads or tails? Enter 1 for heads and 2 for tails.");

            guessString = Console.ReadLine();

            validNumber = byte.TryParse(guessString, out guess);

            //if user input is invalid, prompt agian

            while (validNumber == false)

            {

                Console.WriteLine("You entered an invalid number.");

                Console.WriteLine("Heads or tails? Enter 1 for heads and 2 for tails.");

                guessString = Console.ReadLine();

                validNumber = byte.TryParse(guessString, out guess);

            }

            //if input is not 1 or 2, prompt again

            if (guess != 1)

            {

                if (guess != 2)

                {

                    do 

                    {

                        Console.WriteLine("You entered an invalid number.");

                        Console.WriteLine("Heads or tails? Enter 1 for heads and 2 for tails.");

                        guessString = Console.ReadLine();

                        validNumber = byte.TryParse(guessString, out guess);

                        //if user input is invalid, prompt again

                        while (validNumber == false)

                        {

                        Console.WriteLine("You entered an invalid number.");

                        Console.WriteLine("Heads or tails? Enter 1 for heads and 2 for tails.");

                        guessString = Console.ReadLine();

                        validNumber = byte.TryParse(guessString, out guess);    

                        }

                    }

                    while (((guess == 1) || (guess == 2)) == false);

                }

            }

            //tell user their guess

            Console.Write("You guessed: ");

            //if user guess is heads, output heads

            if (guess == 1)

            {

                Console.Write("heads. ");

            }

            //if user guess is tails, output tails

            if (guess == 2)

            {

                Console.Write("tails ");

            }

            //reveal answer

            Random random = new Random();

            result = (byte)(random.Next(2) + 1);

            Console.Write("The answer is: ");

            if (result == 1)

            {

                Console.WriteLine("heads");

            }

            if (result == 2)

            {

                Console.WriteLine("tails");

            }

            Console.WriteLine("\n");

            //invite the player to play again

            Console.WriteLine("Press \"Run\" to play again.");

        }

    }

}