using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        List<string> list = new List<string> {"Freestyle steel","Freestyle Alloy","Trekking steel uk","Single speed","5 speed","15 speed","3 Speed internal gear with 55 coaster","MTB steel","Junior MTB"};

        foreach(string data in list)

        {

            string regex = @"(\b\w)|(\d+)";

            var matches = Regex.Matches(data, regex, RegexOptions.Multiline);

            string output = "";

            foreach(Match item in matches)

            {

                output += item.Groups[1];

            }

            Console.WriteLine(output);

        }

    }

}