using System;
using Unit4.CollectionsLib;
using System.Linq;
using System.Text;

namespace ConsoleApplication20
{
    class Program
    {
        static void Main(string[] args)
        {
        }
// תרגיל 1
        public static bool checkit(Unit4.CollectionsLib.Stack<int> s)
        {
            Unit4.CollectionsLib.Stack<int> temp = copy(s);
            bool check = false;
                for(int i=0;!temp.IsEmpty();i++)
                {
                   temp.Pop();
                    for(int j=0;temp.IsEmpty();j++)
                    {
                        if (s.Top() == temp.Top())
                        {
                            check = false;
                            s.Pop();


                        }
                        else
                            check = true;


                    }
                }
                return check;

            }
        public static Unit4.CollectionsLib.Stack<int> copy(Unit4.CollectionsLib.Stack<int> s)
        {
            Unit4.CollectionsLib.Stack<int> temp = new Stack<int>();
            Unit4.CollectionsLib.Stack<int> temp1 = new Stack<int>();
            while (!s.IsEmpty())
            {
                temp.Push(s.Pop());
            }
            while (!temp.IsEmpty())
            {
                s.Push(temp.Pop());
                temp.Push(temp.Pop());
            }
            return temp1;
        }

        }
}
// תרגיל 2

using System;
using Unit4.CollectionsLib;
using System.Linq;
using System.Text;

namespace ConsoleApplication22
{
    class Program
    {
        static void Main(string[] args)
        {

        }

        public static int checkSize(Unit4.CollectionsLib.Stack<int> t)
        {
            int count = 0;
            while (!t.IsEmpty())
            {
                count++;
                t.Pop();

            }
            return count;
        }

        public static int CheckMe(Unit4.CollectionsLib.Stack<int> s)
        {
            int countit = (checkSize(s) / 2);
            Unit4.CollectionsLib.Stack<int> temp =Program.copy(s);
            if (checkSize(s) % 2 != 0)
            {
                for (int i = 0; i < countit+1; i++)
                {
                    temp.Pop();
                }


            }
            return temp.Top();

            int sum=0;
            int avg;

            if (checkSize(s) % 2 == 0)
            {
                while (!temp.IsEmpty())
                {
                    temp.Pop();
                    for (int i = 0; i < countit; i++)
                    {
                        sum += temp.Pop();
                        avg = sum / countit;
                    }

                }
            }
            return avg;


        }

        public static Unit4.CollectionsLib.Stack<int> copy(Unit4.CollectionsLib.Stack<int> s)
        {
            Unit4.CollectionsLib.Stack<int> temp = new Stack<int>();
            Unit4.CollectionsLib.Stack<int> temp1 = new Stack<int>();
            while (!s.IsEmpty())
            {
                temp.Push(s.Pop());
            }
            while (!temp.IsEmpty())
            {
                s.Push(temp.Pop());
                temp.Push(temp.Pop());
            }
            return temp1;
        }

    }
}

// תרגיל 3

using System;
using Unit4.CollectionsLib;
using System.Linq;
using System.Text;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
        }

        public static int Sum(Unit4.CollectionsLib.Stack<int> s)
        {
            int sum=0;
            Unit4.CollectionsLib.Stack<int> temp = Program.copy(s);
            while (!temp.IsEmpty())
            {
                sum += temp.Top();
                temp.Pop();
            }
            return sum;
        }

         public static Unit4.CollectionsLib.Stack<int> copy(Unit4.CollectionsLib.Stack<int> s)
      {
            Unit4.CollectionsLib.Stack<int> temp = new Stack<int>();
           Unit4.CollectionsLib.Stack<int> temp1 = new Stack<int>();
           while (!s.IsEmpty())
            {
                temp.Push(s.Pop());
            }
           while (!temp.IsEmpty())
            {
                s.Push(temp.Pop());
              temp.Push(temp.Pop());
            }
          return temp1;
        }
    }
}

// תרגיל 6
using System;
using Unit4.CollectionsLib;
using System.Linq;
using System.Text;

namespace ConsoleApplication79
{
    class Program
    {
        static void Main(string[] args)
        {
        }
        public static Unit4.CollectionsLib.Stack<int> copy(Unit4.CollectionsLib.Stack<int> s)
        {
            Unit4.CollectionsLib.Stack<int> temp = new Stack<int>();
            Unit4.CollectionsLib.Stack<int> temp1 = new Stack<int>();
            while (!s.IsEmpty())
            {
                temp.Push(s.Pop());
            }
            while (!temp.IsEmpty())
            {
                s.Push(temp.Pop());
                temp.Push(temp.Pop());
            }
            return temp1;
        }

        public static Unit4.CollectionsLib.Stack<int> NewS(Unit4.CollectionsLib.Stack<int> s)
        {
            Unit4.CollectionsLib.Stack<int> temp = Program.copy(s);
            Unit4.CollectionsLib.Stack<int> temp1 = new Stack<int>();
            while (!temp.IsEmpty())
            {
                if (s.Top() < temp.Top())
                {

                    temp1.Push(temp.Top());
                    temp.Pop();
                }
            }
            return temp1;
        }

    }
}