using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter grade 1:");

        int grade1 = int.Parse(Console.ReadLine());

        Console.WriteLine("Enter grade 2:");

        int grade2 = int.Parse(Console.ReadLine()); 

        Console.WriteLine("Enter grade 3:");

        int grade3 = int.Parse(Console.ReadLine());

        double avg = (grade1+grade2+grade3)/3;

        if (avg>=90)

        {   Console.WriteLine("your avreage grade in CS is grader than 90! " + "your grade is: " + avg);

        }

        else 

        {   Console.WriteLine("your avreage in CS is smaller than 90 " + "your grade is: " + avg);

        }

    }

}