public static void Main()
Console.WriteLine("عدد الطلاب الذين سجلوا لدوره الكراتيه");
Number_of_children=int.Parse(Console.ReadLine());
if(Number_of_children>15)
Console.WriteLine("Send a message that the course is open");
Console.WriteLine("Show subscriber count");
Console.WriteLine("Send a message that there are few subscribers");
Console.WriteLine("Show how many subscribers the period is missing");