using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter Marks:");

        double marks = Convert.ToDouble(Console.ReadLine());

        if(marks >= 80)

        {

            Console.WriteLine("The grade is A");

        }

        else if(marks >=50)

        {

            Console.WriteLine("The grade is P");

        }

        else

        {

            Console.WriteLine("The grade is F");

        }

    }

}