using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string pattern = @"\(([^\)]+)\)";

        string input = @"x^(3*x+1) + (cos x)";

        RegexOptions options = RegexOptions.IgnoreCase;

        foreach (Match m in Regex.Matches(input, pattern, options))

        {

            Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);

        }

    }

}