Series of Letters

// Write a program that reads a string from the console and replaces all series of consecutive identical letters with a single one.

namespace _01.SeriesOfLetters
{
    using System;
    using System.Text;
    using System.Text.RegularExpressions;

    class SeriesOfLetters
    {
        static void Main(string[] args)
        {
            string text = Console.ReadLine();
            string pattern = @"(?<letter>\w)\1+";
            MatchCollection matches = Regex.Matches(text, pattern);
            StringBuilder sb = new StringBuilder(text);
            foreach (Match match in matches)
            {
                sb.Replace(match.ToString(), match.Groups["letter"].Value.ToString());
            }

            Console.WriteLine(sb);
        }
    }
}