using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Please write your basic grade");

        double grade = double.Parse(Console.ReadLine());

        Console.WriteLine("Please write your number of absences in the semester");

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

        if (absence > 30)

        {

            grade = 40;

        }

        else if (absence >= 21)

        {

            grade = grade - 10;

        }

        else if (absence >= 15)

        {

            grade = grade - 5;

        }

​

        Console.WriteLine("Your grade is {0}", grade);

    }

}