using System;   

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Please enter a Physics marks:");

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

        if(marks > 90)

        {

            Console.WriteLine("You got A grade");

        }

        else if(marks >50 && marks <90){

            Console.WriteLine("You got B grade");

        }

        else{

            Console.WriteLine("You got C grade");

        }

    }

}