using System;

public class Program

{

    //  A typical d20 has a minimum value of 1 and a maximum of 20:

    public const long MINIMUM_DIE_VALUE = 1;

    public const long MAXIMUM_DIE_VALUE = 20;

    public static void RunExample()

    {

        Report(

                    10

                ,   5

                ,   1

            );

        Report(

                    17

                ,   5

                ,   1

            );

    }

    public static void Report(

                long dc

            ,   long bonus_normal

            ,   long bonus_advantage

        )

    {

        var stringMessage = 

                    "For\tDC = "

                +   dc.ToString()

                +   "\tBonus (normal) = "

                +   bonus_normal.ToString()

                +   "\tBonus (advantage) = "

                +   bonus_advantage.ToString()

                +   ":"

                +   System.Environment.NewLine

            ;

        if (ShouldRollWithAdvantage(

                    dc

                ,   bonus_normal

                ,   bonus_advantage

            ))

        {

            stringMessage += "Your odds are better with the power of ADVANTAGE!";

            //Console.WriteLine("Your odds are better with the power of ADVANTAGE!");

        }

        else

        {

            stringMessage += "Advantage is for losers; roll normally!";

            //Console.WriteLine("Advantage is for losers; roll normally!");

        }

        Console.WriteLine(stringMessage);

        Console.WriteLine();

    }

    public static bool ShouldRollWithAdvantage(

                long dc

            ,   long bonus_normal

            ,   long bonus_advantage

        )

    {

        //  Case 1:

        //      If rolling with advantage can't succeed, then just roll normally.

        //      Doesn't matter if rolling normally can't succeed, either, because if

        //      you're going to fail either way, may as well only roll once.

        if (dc - bonus_advantage > MAXIMUM_DIE_VALUE)

        {

            return false;

        }

        //  Case 2:

        //      If rolling without advantage can't succeed, then roll with advantage.

        if (dc - bonus_normal > MAXIMUM_DIE_VALUE)

        {

            return true;

        }

        //  Case 3:

        //      If rolling without advantage always succeeds, then roll without advantage.

        if (dc - bonus_normal <= MINIMUM_DIE_VALUE)

        {

            return false;

        }

        //  Case 4:

        //      If rolling with advntage always succeeds, then roll with advantage.

        if (dc - bonus_advantage <= MINIMUM_DIE_VALUE)

        {

            return true;

        }

        //  Case 5:

        //      Since rolling with advantage and rolling without advantage are both

        //      possible-but-not-guaranteed, we compare their odds of success.

        //      

        //      This method checks if

        //          (DC - bonus_advantage - 1)^2

        //      is less than

        //          20 * (DC - bonus_normal - 1)

        //      instead of the fraction to avoid floating-point values.

        {

            var leftHandSide = (dc - bonus_advantage - MINIMUM_DIE_VALUE);

            leftHandSide *= leftHandSide;

            var rightHandSide = (MAXIMUM_DIE_VALUE - MINIMUM_DIE_VALUE + 1) * (dc - bonus_normal - MINIMUM_DIE_VALUE);

            var shouldRollWithAdvantage = leftHandSide < rightHandSide;

            return shouldRollWithAdvantage;

        }

    }

    private static bool TryValidateProgramConstants(

                out string errorMessage

        )

    {

        if (!(MINIMUM_DIE_VALUE < MAXIMUM_DIE_VALUE))

        {

            errorMessage = "Maximum die value must be greater than minimum die value.";

            return false;

        }

        if (MINIMUM_DIE_VALUE < -1000)

        {

            errorMessage = "Unreasonably low minimum die value.";

            return false;

        }

        if (MAXIMUM_DIE_VALUE > 1000)

        {

            errorMessage = "Unreasonably high maximum die value.";

            return false;

        }

        errorMessage = default(string);

        return true;

    }

    public static void Main()

    {

        string errorMessage;

        if (TryValidateProgramConstants(out errorMessage))

        {

            RunExample();

        }

        else

        {

            Console.WriteLine("Error in program validation; aborting run.");

            if (!string.IsNullOrWhiteSpace(errorMessage))

            {

                Console.WriteLine(errorMessage);

            }

        }

    }

}