using System;
using System.Linq;
using System.Collections.Generic;
using System.Text.RegularExpressions;
public class Test
{
	public static void Main()
	{
		var HASHTAG_LETTERS = @"\p{L}\p{M}";
	    var HASHTAG_NUMERALS = @"\p{Nd}";
	    var HASHTAG_SPECIAL_CHARS = @"_\u200c\u200d\ua67e\u05be\u05f3\u05f4\uff5e\u301c\u309b\u309c\u30a0\u30fb\u3003\u0f0b\u0f0c\u00b7";
	    var HASHTAG_LETTERS_NUMERALS = HASHTAG_LETTERS + HASHTAG_NUMERALS + HASHTAG_SPECIAL_CHARS;
	    var HASHTAG_LETTERS_NUMERALS_SET = "[" + HASHTAG_LETTERS_NUMERALS + "]";
	    var HASHTAG_LETTERS_SET = "[" + HASHTAG_LETTERS + "]";
	    var VALID_HASHTAG = new Regex("(^|[^&" + HASHTAG_LETTERS_NUMERALS + @"])(#|\uFF03)(?!\uFE0F|\u20E3)(" + HASHTAG_LETTERS_NUMERALS_SET + "*" + HASHTAG_LETTERS_SET + HASHTAG_LETTERS_NUMERALS_SET + "*)", RegexOptions.IgnoreCase);
	    
	    var tests = new List<string>() {"#hashtag",
			"#Azərbaycanca",
			"#mûǁae",
			"#Čeština",
			"#Ċaoiṁín",
			"#Caoiṁín",
			"#táim",
			"#hag̃ua",
			"#café",
			"#עברית",
			"#אֲשֶׁר",
			"#עַל־יְדֵי",
			"#וכו׳",
			"#מ״כ",
			"#العربية",
			"#حالياً",
			"#يـﮱـَٱ",
			"#ประเทศไทย",
			"#ฟรี",
			"#日本語ハッシュタグ",
			"＃日本語ハッシュタグ",
			"これはOK #ハッシュタグ",
			"これもOK。#ハッシュタグ",
			"これはダメ#ハッシュタグ",
			"#1",
			"#2"};
		tests.ForEach(input =>
			Console.WriteLine("Input: " + input + " = " + VALID_HASHTAG.IsMatch(input) +
			  (VALID_HASHTAG.IsMatch(input) ? ", match = " + VALID_HASHTAG.Match(input).Value : "")));
	}
}