using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter a letter grade: ");

        var input = Console.ReadLine();

        if(!(int.TryParse(input, out int result)))

            {

            input = input.ToUpper();

        if(Char.TryParse(input, out char letter))

        { 

            switch(letter)

            {

                case 'A':

                    Console.WriteLine("Excellent");

                    break;

                case 'B':

                    Console.WriteLine("Good");

                    break;

                case 'C':

                    Console.WriteLine("Passing");

                    break;

                case 'D':

                    Console.WriteLine("Your almost there");

                    break;

                case 'F':

                    Console.WriteLine("Good Try");

                    break;

                default:

                    Console.WriteLine("Sorry but that is not a vaild input");

                    break;

            }

        }

        else

        {

            Console.WriteLine("Sorry but that is not a vaild input");

        }

    }

        else

        {

            Console.WriteLine("Sorry but that is not a vaild input");

        }

    }

}