Regex Class Answer for Stack Overflow

namespace RegexTest
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text.RegularExpressions;
    internal class Program
    {
        private static void Main(string[] args)
        {
            const string File1 = "You are very beautiful, can you give me your number?";
            const string File2 = "Beautiful is Beyonce, not me.";
            const string FindWordsRegex = @"\b\w+\b";
            var GetWords = new Regex(FindWordsRegex, RegexOptions.IgnoreCase | RegexOptions.Compiled);
            var file1Words = GetWords.Matches(File1).OfType<Match>().ToList();
            Console.WriteLine("file1Words:");
            file1Words.ForEach(w => Console.WriteLine(w));
            var file2Words = GetWords.Matches(File2).OfType<Match>().ToList();
            Console.WriteLine("file2Words:");
            file2Words.ForEach(w => Console.WriteLine(w));
            var words = new List<string>();
            file1Words.ForEach(a => file2Words.ForEach(b => { if (string.Compare(a.Value, b.Value, true) == 0)  words.Add(a.Value); }));
            Console.WriteLine("words:");
            words.ForEach(w => Console.WriteLine(w));
            var ReplaceRegex = string.Format("(?={0})", words[0]);
            Console.WriteLine("Replace Regex == \"{0}\"", ReplaceRegex);
            var Search = new Regex(ReplaceRegex, RegexOptions.Compiled | RegexOptions.IgnoreCase);
            Console.WriteLine("Replace Target: {0}", words[0]);
            var r2 = Search.Matches(File1);
            var result = Search.Replace(File1, File2);
            Console.WriteLine("Final Result: {0}\r\n", result);
            Console.WriteLine("Press Enter To Quit");
            Console.ReadLine();
        }
    }
}