using System;

using System.Text.RegularExpressions;

​

public class GenExpressoLiteRegex

{

    const string pattern = @"(\w+)";

    const RegexOptions options = RegexOptions.Singleline;

    private static readonly Regex myRegex = new Regex(pattern, options);

​

    public static void Main()

    {

        string input = @"Lorem"; //END_INPUT

        string substitution = @"Lorem $1 AAA \$1 BBB $1 Lorem";

​

        string result = myRegex.Replace(input, substitution);

​

        Console.WriteLine(result);

    }

}