using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var text1 = "\\left(\\begin{array}{cc} \\frac{1}{3} & x\\\\ \\mathrm{e}^{x} &... x^2 \\end{array}\\right)";

        var text2 = "\\left(\\begin{array}{cc} \\frac{1}{3} & x\\\\ \\mathrm{e}^{x} &... x^2 \\end{array}\\right";

        var text3 = "\\left(\\begin{array}{cc} \\frac{1}{3} & x\\\\ \\mathrm{e}^{x &... x^2 \\end{array}\\right)}";

        Console.WriteLine(IsPaired(text1));

        Console.WriteLine(IsPaired(text2));

        Console.WriteLine(IsPaired(text3));

    }

    private static Dictionary<char, char> _pairs = new Dictionary<char, char> 

    {

        { '(', ')' },

        { '[', ']' },

        { '{', '}' },

    };

    public static bool IsPaired(string input)

    {

​

        // If input is empty string then return true

        if (input.Length == 0) { return true;}

​

        Stack<char> brackets = new Stack<char>();

​

        // Loop through each character

        foreach (char i in input)

        {

            // If it is an opening bracket, push it to the stack

            if(_pairs.ContainsKey(i)){

                brackets.Push(i);

            }

            // If it is an closing bracket, pop it

            else if(_pairs.Values.Contains(i))

            {

                var openingBracket = brackets.Pop();

                // If it isn't pair of the last opening bracket return false

                if(_pairs[openingBracket] != i) 

                {

                    return false;

                }

            }

        }

        // The stack should be empty in case all brackets are closed

        return brackets.Count == 0;

    }

}