using System;

using System.Collections;

​

public class Program

{

    Stack stc = new Stack();

    public void ValidString(string str)

    {

        char[] ch = str.ToCharArray();

        int open = 0;

        int close = 0;

        for (int i = 0; i < ch.Length; i++)

        {

            if (ch[i].ToString() == "(")

            {

                open++;

            }

            else

            {

                close++;

            }

        }

​

        if (open < close)

        {

            Console.WriteLine(open + open);

        }

        else

        {

            Console.WriteLine(close + close);

        }

    }

​

    public static void Main()

    {

        string str = "()(())(";

        Program obj = new Program();

        obj.ValidString(str);

    }

}