using System;

public class Program

{

    public static void Main()

    {

            Console.WriteLine("Enter your major: ");

            string major = Console.ReadLine();

​

            Console.WriteLine("Enter your score: ");

            string scoreInput = Console.ReadLine();

            int score;

​

            if (!int.TryParse(scoreInput, out score))

            {

                Console.WriteLine("Error: Invalid score, must be a whole number.");

                return;

            }

​

            if (score < 0 || score > 100)

            {

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

                return;

            }

​

            if (score >= 90)

            {

                Console.WriteLine("You get A");

​

                if (major == "Information Systems")

                {

                    Console.WriteLine("Congratulations! You are one of the best students in IS.");

                }

                else

                {

                    Console.WriteLine("Congratulations! You are one of the best students.");

                }

            }

            else if (score >= 80)

            {

                Console.WriteLine("You get B");

            }

            else if (score >= 70)

            {

                Console.WriteLine("You get C");

            }

            else if (score >= 60)

            {

                Console.WriteLine("You get D");

            }

            else

            {

                Console.WriteLine("You get F");

            }

        }

    }