Sumor

using System;

namespace AddRemoveTest
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var a = new A();
            a.MyEvent += (s,e) => {Console.WriteLine("Event");};
            
            
            a.MyEvent -= (s,e) => {Console.WriteLine("Event");};
        }
    }
    
    public class A
    {
        public event EventHandler MyEvent
        {
            add{
                
                Console.WriteLine("Add event");
            }
            remove{
                Console.WriteLine("Remove event");
            }
        }
    }
}
// Вывод:
// Add event
// Remove event

var str = "Толщина: 9 см<br><br>Длина: 160 см<br>Ширина: 70 см<br>Детские:Да<br><br>Детские:Да<br><br>Детские:Да<br><br>Детские:Да<br>";

foreach(var s in str.Split(new string[] {"<br>"}, StringSplitOptions.RemoveEmptyEntries).Distinct())            
    Console.WriteLine(s);

// Подсчёт
var str = "ТОСТЕР";
var result = 0;
foreach(var ch in str)
{
    result |= (1 << ((int)ch - (int)'А'));
}

// Вывод результата
for(var i = 0; i < 32; i++)
{
    if((result & (1 << i)) == (1 << i))
        Console.WriteLine((char) ((int)'А' + i));
}
// Вывод:
// Е
// О
// Р
// С
// Т

private List<System.DayOfWeek> _dayWeeks = new List<System.DayOfWeek>();
public List<System.DayOfWeek> DayWeeks
{
  get{return _dayWeeks;}
}

public bool HasMonday
{
  get{ return _dayWeeks.Any(d => d  == DayOfWeek.Monday);}
  set
  {
    if(value && !HasMonday)
    {
      _dayWeeks.Add(DayOfWeek.Monday);
      OnPropertyChanged("DayWeeks");
      OnPropertyChanged("HasMonday");     
    }
    if(!value && HasMonday)
    {
      _dayWeeks.Remove(DayOfWeek.Monday);
      OnPropertyChanged("DayWeeks");
      OnPropertyChanged("HasMonday");     
    }
  }
}
// Дальше аналогично для других дней недели

using System.Runtime.InteropServices;

[DllImport("myDll.dll", CallingConvention=CallingConvention.StdCall)]
public static extern int Card();

[DllImport("myDll.dll", CallingConvention=CallingConvention.StdCall, Charset=Charset.Ansi)]
public static extern int cudaCard(IntPtr mWnd, IntPtr aWnd, string data, string parms, bool show, bool nopause);

class A
{
 public string Name{get;set;}
 public A Parent {get;set;}
 public IEnumerable<A> Children
 {
  get
  {
    return AllItemsOfA.Select(a => a.Parent == this);
  }
 }
 public int Level()
 {
  int level = 0;
  var current = Parent;
  while(current != null)
  {
    current = current.Parent;
    level ++;
  }
  return level;
 }
}