class Zbior
    {
        private Hashtable hashtable;
        public Zbior()
        {
            hashtable = new Hashtable();
        }
        public void Dodaj(object item)
        {
            hashtable.Add(item, 1);
        }
        public Zbior Union(Zbior union)
        {
            Zbior z = new Zbior();
            foreach (DictionaryEntry item in union.hashtable)
            {
                z.Dodaj(item.Key);
            }
            foreach (DictionaryEntry item in hashtable)
            {
                if (!z.hashtable.Contains(item.Key))
                {
                    z.Dodaj(item.Key);
                }
            }
            return z;
        }
        public Zbior Intersection(Zbior zbior)
        {
            Zbior z1 = new Zbior();
            foreach (DictionaryEntry item in zbior.hashtable)
            {
                if (hashtable.Contains(item.Key))
                    z1.Dodaj(item.Key);
            }
            return z1;
        }
        public Zbior Difference(Zbior zbior)
        {
            Zbior z2 = new Zbior();
            foreach (DictionaryEntry item in hashtable)
            {
                if (!zbior.hashtable.Contains(item.Key))
                    z2.Dodaj(item.Key);
            }
            return z2;
        }
        public void Display()
        {
            foreach (DictionaryEntry item in hashtable)
            {
                Console.Write(item.Key+" ");
            }
        }
    }
 static void Main(string[] args)
        {
            Zbior z1 = new Zbior();
            Zbior z2 = new Zbior();
            int[] Tab1 = { 1, 3, 5, 7, 9 };
            int[] Tab2 = { 2, 4, 6, 8 };
            foreach (var item in Tab1)
            {
                z1.Dodaj(item);
            }
            foreach (var item in Tab2)
            {
                z2.Dodaj(item);
            }
            Console.Write("Zbiór A:");
            z1.Display();
            Console.Write("\nZbiór B:");
            z2.Display();

            Zbior z3 = z1.Union(z2);
            Console.Write("\nA + B: ");
            z3.Display();

            Zbior z4 = z3.Intersection(z1);
            Console.Write("\n(A+B)*A: ");
            z4.Display();

            Zbior z5 = z3.Difference(z1);
            Console.Write("\n(A+B)-A: ");
            z5.Display();
            Console.ReadKey();
        }