اكتب برنامج بلغة سي شارب c# لحساب المتوسط الحسابي

using System;
class HelloWorld {
  static void Main() {

        int total,       // sum of grades            
        gradeCounter,    // number of grades entered          
        gradeValue;      // grade value 
        double average;      // average of all grades 
 
        // initialization phase 
        total = 0;           // clear total        
        gradeCounter = 0;    // prepare to loop 
 
        // processing phase 
        // prompt for input and convert to integer 
        Console.Write("Enter Integer Grade, -1 to Quit: ");         
        gradeValue = Int32.Parse(Console.ReadLine()); 
 
        // loop until a -1 is entered by user         
        while (gradeValue != -1) 
        { 
            // add gradeValue to total             
            total = total + gradeValue; 
 
            // add 1 to gradeCounter 
            gradeCounter = gradeCounter + 1; 
 
            // prompt for input and read grade from user 
            // convert grade from string to integer 
            Console.Write("Enter Integer Grade, -1 to Quit: ");             
            gradeValue = Int32.Parse(Console.ReadLine()); 
        } // end while 
 
        // termination phase         
        if (gradeCounter != 0) 
        { 
            average = (double)total / gradeCounter; 
            // display average of exam grades 
            Console.WriteLine("\nClass average is "+ average); 
        }         
        else 
        { 
            Console.WriteLine("No grades were entered."); 
        }
  }
}