using System;

using System.Text.RegularExpressions;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        string averylongsentence = "Explore results with the Tools below. Replace & List output custom results. Details lists capture groups. Explain describes your expression in plain English.";

        string[] words = averylongsentence.Split(' ').Take(20).ToArray();

        System.Console.WriteLine( String.Join(" ",words) );

    }

}