using System;

public class Program

{

    public static void Main()

    {

         double score = 1;

        while (score > 0)  //loop is for testing multiple inputs wihout needing to run program repeatedly

        {   

            Console.WriteLine("Hello World");

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

            if (score > 0 && score <= 100)

                ComputeGrade(score);

            else if (score == 0)

                Console.WriteLine("Goodbye");

            else

                Console.WriteLine("Score values must be between 0 and 100.");

    }

}

    // for computing the letter grade with a parameter score

    private static void ComputeGrade(double score)

    {

        char letter;

        if (score >= 90)

            letter = 'A';

        else if (score >= 80)

            letter = 'B';

        else if (score >= 70)

            letter = 'C';

        else

            letter = 'D';

        Console.WriteLine(" 92 " + letter);

    }

​

}