using System;

public class Program

{

    public static void Main()

    {

        int grade, total, acount, bcount, fcount, grdcounter, input;

        float avggrade;

        total=0;

        acount = 0;;

        bcount = 0;

        fcount = 0;

        grdcounter = 0;

        grade = 0;

    Console .WriteLine("Please enter 1 to continue or -1 to exit");

        input= int.Parse(Console.ReadLine());

        while (input!= -1)

        {

            Console.WriteLine("Please enter a grade within the range 0 to 100");

              input= int.Parse(Console.ReadLine());

            total = total + grade;

            if(grade >= 80 && grade <=100)

                    { acount = acount +1;

            }  else if ( grade >= 60 && grade <=79)

                       { bcount = bcount +1;

            } else {

                     fcount = fcount +1;

            }

    Console .WriteLine("Please enter 1 to continue or -1 to exit");

        input= int.Parse(Console.ReadLine());

        }//end while        

        avggrade = total /grdcounter;

        Console.WriteLine("Number of A's = " + acount);

        Console.WriteLine("Number of B's = " + bcount);

        Console.WriteLine("Number of F's = " + fcount);

        Console.WriteLine("the average is " + avggrade);

    }

}