using System;
using System.Linq;

abstract class Customer
    {
        public int id;
        public string name;
        public double balance;
    }

    class NormalCustomer: Customer
    {
    }

    class SubscriberCustomer:Customer
    {
       public int LandMinutes;
       public int MobileMinutes;
    }

public class Test
{
	public static void Main()
	{
	    Customer[] customers = new Customer[5];
        customers[0]=new NormalCustomer();
        customers[1] = new NormalCustomer();
        customers[2] = new SubscriberCustomer();
        customers[3] = new NormalCustomer();
        customers[4] = new SubscriberCustomer(); 
		
		var groupedCustomers = customers.GroupBy(c => c.GetType()).ToList();
        
        foreach(var type in groupedCustomers)
        {
           Console.WriteLine(type.Key.Name + ", count: " + type.Count());
        }
	}
}