using System;

public class Program

{

    public static void Main()

    {

        int Marks;

        Console.WriteLine("You Must Enter the marks for grade");

        Console.WriteLine("Enter a number:  ");

        //Read the first number and grade

        Marks = Convert.ToInt32(Console.ReadLine());

        if(Marks>80)

        {

            Console.WriteLine("Grade is A");

        }

        else if(Marks<70)

        {

            Console.WriteLine("Grade is B");

        }

        else if(Marks<60)

        {

                Console.WriteLine("Grade is C");

        }

    }

}