using System;
using System.Text.RegularExpressions;
 
namespace RegExApplication
{
   public class Program
   {
      public static void Main(string[] args)
      {
      	string input = "NNTSY";
        Regex regex = new Regex("(?=N[^P][ST][^P]).", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
 
 
         Match match = regex.Match(input);
 
        	while (match.Success)
        	{
            	Console.WriteLine(input.Substring(match.Index, 4));
            	match = match.NextMatch();
        	}
      }
   }
}

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