using System;

using System.Collections;

public class Program

{

    public static void Main()

    {

        Stack stack = new Stack();

        //Console.WriteLine("Hello World");

        string input ="<>[]{}()(";

        char [,] pair = { {'<', '>'}, {'(', ')'}, {'{', '}'}, {'[', ']'}};

        foreach(char ic in input){

            for(int i = 0; i< 4; i++ ){

                if(ic == pair[i, 0] || ic == pair[i, 1]){

                    stack.Push(ic);

                    if(stack.Count >2){

                    }   

                }

            }

        }

    }

}