using System;

using System.Data;

using System.Text.RegularExpressions;

using System.Xml;

public class Program

{

    public static void Main()

    {

        string input = "20 * (6+3) / ((4+6)*9)";

        Console.WriteLine(input);

        DataTable dt = new DataTable();

        Regex rx = new Regex(@"\([^()]*\)");

        string expression = input;

        while (rx.IsMatch(expression))

        {

            expression = rx.Replace(expression, m => dt.Compute(m.Value, null).ToString(), 1);

            Console.WriteLine(expression);

        }

        Console.WriteLine(dt.Compute(expression, null));

    }

}