Decorator Design Pattern, C#

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//Title of this code
//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Pizza pizza = new LargePizza();
            Console.WriteLine(pizza.GetDescription());
            Console.WriteLine(pizza.CalculateCost());
            pizza = new Chees(pizza);
            Console.WriteLine(pizza.GetDescription());
            Console.WriteLine(pizza.CalculateCost());
            pizza = new Ham(pizza);
            Console.WriteLine(pizza.GetDescription());
            Console.WriteLine(pizza.CalculateCost());
        }
        public abstract class Pizza
        {
            public string Description{get; set;}
            public abstract string GetDescription();
            public abstract double CalculateCost();
        }
        public class LargePizza : Pizza
        {
            public LargePizza()
            {
                    Description = "Large Pizza";
            }
            public override string GetDescription()
            {
                return Description;
            }
            
            public override double CalculateCost()
            {
                return 10.00;
            }
        }
        
        public class PizzaDecorator : Pizza
        {
            protected Pizza _pizza;
            public PizzaDecorator(Pizza pizza)
            {
                _pizza = pizza;
            }
            public override string GetDescription()
            {
                return _pizza.Description;
            }
            public override double CalculateCost()
            {
                return _pizza.CalculateCost();
            }
            
        }
        public class Chees : PizzaDecorator
        {
            public Chees(Pizza pizza): base (pizza)
            {
                Description = "Chees";
            }
            public override string GetDescription()
            {
                return _pizza.GetDescription() + ", " + Description;
            }
            public override double CalculateCost()
            {
                return _pizza.CalculateCost()+2.00;
            }
            
        }
        
        public class Ham : PizzaDecorator
        {
            public Ham(Pizza pizza): base (pizza)
            {
                Description = "Ham";
            }
            public override string GetDescription()
            {
                return _pizza.GetDescription() + ", " + Description;
            }
            public override double CalculateCost()
            {
                return _pizza.CalculateCost()+2.00;
            }
            
        }
        
            
    }
}

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Compilation time: 0.08 sec, absolute running time: 0.08 sec, cpu time: 0.08 sec, average memory usage: 16 Mb, average nr of threads: 4