Regex

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;
  class Program
    {
        static void Main()
        {
            string keyword = Console.ReadLine();
            string userInput = Console.ReadLine();
            string pattern = string.Format(@"([^.!?])+( {0} )([^.!?])*", keyword);

            MatchCollection matches = Regex.Matches(userInput, pattern);

            foreach(var match in matches)
            {
                Console.WriteLine(match);
            }

        }
    }