using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace TodoApplication
{
    public class LimitedSizeStack<T>
    {
        protected int limit;
        protected int counter = 0;
        protected StackItem<T> head;
        protected StackItem<T> tail;

        public LimitedSizeStack(int limit)
        {
            this.limit = limit;
        }

        public void Push(T item)
        {
            if (Overcame)
            {
                head = head.Next;
                Push(item);
            }
            else
            {
                if (head == null && tail == null)
                {
                    head = tail = new StackItem<T> { Value = item };
                    counter += 1;
                }
                else
                {
                    if (Count == 1)
                    {
                        if (tail == null)
                        {
                            tail = new StackItem<T> { Value = item };
                            head.Next = tail;
                            counter += 1;
                        }
                        else
                        {
                            tail.Next = new StackItem<T> { Value = item };
                            tail = tail.Next;
                            counter += 1;
                        }
                    }
                    else
                    {
                        if (tail == null)
                        {
                            counter += 1;
                            tail = new StackItem<T> { Value = item };
                        }
                        else
                        {
                            tail.Next = new StackItem<T> { Value = item };
                            tail = tail.Next;
                            counter += 1;
                        }
                    }
                }
            }
        }

        public T Pop()
        {
            T crutch = tail.Value;
            tail = null;
            counter -= 1;
            return crutch;
        }

        protected bool Overcame
        {
            get
            {
                if (Count == limit) return true;
                else return false;
            }
        }

        public int Count
        {
            get
            {
                return counter;
            }
        }
    }

    public class StackItem<T>
    {
        public T Value
        {
            get;
            set;
        }

        public StackItem<T> Next
        {
            get;
            set;
        }
    }
}