using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        // 1. No, you will get a compilation error if you try to use a double type on a switch statement

        // 2. No, you will get a compilation error.

        // 3. No, cases in switch statements must be constant values, not variables or expressions

        // 4. 

        Console.WriteLine("Please enter your major");

        string Stu_Major = Console.ReadLine();

        Console.WriteLine("Please enter your grade");

        int intGrade;

        string letGrade = "";

        string strGrade = Console.ReadLine();

        bool IsValidNumber = Int32.TryParse(strGrade, out intGrade);

        if (IsValidNumber == false)

        {

            Console.WriteLine("Please enter a valid number!");

            return;

        }

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

        {

            if (intGrade >= 90)

        {

             letGrade = "A";

        }

        else if (intGrade >= 80)

        {

            letGrade = "B";

        }

        else if (intGrade >= 70)

        {

            letGrade = "C";

        }       

        else if (intGrade >= 60)

        {

            letGrade = "D";

        }

        else

        {

             letGrade = "F";

        }

        }

        else

        {

            Console.WriteLine("Please enter a grade between 0 and 100");

        }

        Console.WriteLine("You get {0}", letGrade);

    }

}