Стек как динамическая структура данных

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

namespace ConsoleApplication1
{
    public class Stack
    {
        public char Str;
        public Stack Next;
        public void add(char Str)
        {
            Stack Q = new Stack();
            Q.Str = this.Str;
            this.Str = Str;
            Q.Next = this.Next;
            this.Next = Q;
            Count = Count + 1;

        }
        public char pop()
        {
            char q = this.Str;
            this.Str = this.Next.Str;
            this.Next = this.Next.Next;
            Count = Count - 1;
            return q;
        }
        public int Count;  // Перехватов Д. 09мос(у)
    }

    class Program
    {

        static void Main(string[] args)
        {
            string str;
            char c;
            int w=0;
            bool t = false;
            Stack s = new Stack();
            str = Console.ReadLine();

            for (int i = 0; i < str.Length; i++)
            {
                if ((str[i] == '{') || (str[i] == '(') || (str[i] == '['))
                {
                    s.add(str[i]);
                }
                else if ((str[i] == ')') || (str[i] == ']') || (str[i] == '}'))
                {

                    if (s.Count == 0)
                    {

                        Console.WriteLine("Не хватает скобки");
                        break;
                    }

                    c = (char)s.pop();

                    if (((c == '{') && (str[i] == '}')) ||
                        ((c == '[') && (str[i] == ']')) ||
                        ((c == '(') && (str[i] == ')')))
                    {
                        if (w == (str.Length - 1)/2 ) t = true;
                        w++;
                        continue;
                    }
                    else
                    {
                        Console.WriteLine("Неправильная комбинация скобок");
                        break;
                    }
                }
                else
                {
                    continue;
                }
            }

            if (s.Count > 0)
            {

                Console.WriteLine("Не хватает закрывающей скобки");
            }
            if (t) Console.WriteLine("Все верно!!!");

        }
    }
}