using System;

using System.Collections.Generic;

​

namespace letscompile

{

    public class Program

    {

        public static Tuple<char?, int?> FindRoot(string s)

        {

            int numOpenBrackets = 0;

            if (s.Length == 0) { return new Tuple<char?, int?>(null,null); }

            if (s[0] != '(') { return new Tuple<char?,int?>(null,Int32.Parse(s)); }

            Stack<Tuple<char?,int?>> scanned = new Stack<Tuple<char?,int?>>();

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

            {

                if (s[i] == '(') { numOpenBrackets = numOpenBrackets + 1; }

                if (s[i] != ')') { scanned.Push(new Tuple<char?,int?>(s[i], i)) ;}

                if (s[i] == ')')

                {

                    if (numOpenBrackets > 1) 

                    {

                        while (scanned.Peek().Item1 != '(') { scanned.Pop(); }

                        scanned.Pop();

                        numOpenBrackets = numOpenBrackets - 1;

                    }

                }

            }

            return new Tuple<char?, int?>(scanned.Peek().Item1, scanned.Peek().Item2);

        }

​

        public static void Main(string[] args)

        {

            Console.WriteLine(FindRoot("(23+(590-(36+7)))"));

            Console.WriteLine(FindRoot("((3-98)*(14+7890))"));

            Console.WriteLine(FindRoot("((3-98)/(14/7890))"));

            Console.WriteLine(FindRoot("((23+(590-(36+7)))*(8765-121))"));

            //Console.ReadLine();

        }

    }

}

​