using System;

using System.Collections.Generic;

​

public class Program

    {

        public static void Main(string[] args)

        {

            string MyFirstName = "Kwame";

            var sentence = "This is going to be a really really really really really long text sentence.";

            // Console.WriteLine(string.Format("Hello World {0}", MyFirstName));

            const int maxlength = 20;

            if (sentence.Length < maxlength)

                    Console.WriteLine(sentence);

                else

                {

                    var words = sentence.Split(' ');

                    var totalCharacters = 0;

                    var summaryWords = new List<string>();

                        foreach (var word in words)

                            {

                            totalCharacters += word.Length + 1;

                                if (totalCharacters > maxlength)

                                    break;

                            }

                    var summary = String.Join(" ", summaryWords) + "...";

                    Console.WriteLine(summary);

                }   

        }

    }

​