using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var text = "One word, duel. Limes said bye.";
    	var pattern = @"\b(?<w>\p{L}+)(?:\P{L}+(?<w>(\p{L})(?<=\1\P{L}+\1)\p{L}*))+\b";
    	var result = Regex.Match(text, pattern, RegexOptions.IgnoreCase)?.Groups["w"].Captures
    			.Cast<Capture>()
    			.Select(x => x.Value);
        Console.WriteLine(string.Join(", ", result));
	}
}