using System;

public class Program

{

    /*

    Design and implement a program that asks the user to enter 3 quiz scores (out of 50),

    calculates and displays the average score and the average percentage as well as a letter grade.

    >= 90 is an A

    between 80 and 90 is a B

    between 70 and 80 is a C

    below 70 is an F

    The program should display an error message and allow the user to reenter any scores

    that are not whole numbers between 0 and 50.

    */

    public static void Main()

    {

        int score1, score2, score3;

        score1 = GetScore();

        score2 = GetScore();

        score3 = GetScore();

        double averageScore = (score1 + score2 + score3)/3;

        double averagePercentage = averageScore / 50 * 100;

        string letterGrade = DetermineLetterGrade(averagePercentage);

        Console.WriteLine("\nHere's your grade: " + letterGrade);

        Console.ReadLine();

    }

    //                 GetScore Method

    static int GetScore()

    {

        bool isInt = false;

        int score;

        do

        {

            Console.WriteLine("Pleae enter a score of 50 or less: ");

            string input = Console.ReadLine();

            isInt = int.TryParse(input, out score);

        }

        while (!(isInt && score >= 0 && score <= 50));

        return score;

    }

    //                 DetermineLetterGrade Method

    static string DetermineLetterGrade(double averagePercentage)

    {

        string letterGrade;

        if (averagePercentage >= 90)

            letterGrade = "A";

        else if (averagePercentage >= 80)

            letterGrade = "B";

        else if (averagePercentage >= 70)

            letterGrade = "C";

        else

            letterGrade = "D";

        return letterGrade;

    }

}