using System;

public class Program

{

    public class ScoreIsLessException : Exception{

         public ScoreIsLessException(string message): base(message) {}

    }

    public static void Main()

    {

        int score = 80;

        if (score < 50){

            throw (new ScoreIsLessException("This score is too low. You failed the exam."));

        } else {

        Console.WriteLine("You passed the exam. Congratulations.");

        }

    }

}