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

public class Test
{
	public static void Main()
	{
		var keyword = "A+";
		Console.WriteLine("Unambiguous WB: " + Regex.Replace("A+B and A++", $@"(?<!\w){Regex.Escape(keyword)}(?!\w)", "<b>$&</b>"));
		keyword = "Hello";
		Console.WriteLine("Regular WB: " + Regex.Replace("Hello World! Hello,World!", $@"\b{keyword}\b", "<b>$&</b>"));
		Console.WriteLine("Whitespace WB: " + Regex.Replace("Hello, Hello Hello!", $@"(?<!\S){Regex.Escape(keyword)}(?!\S)", "<b>$&</b>"));
		keyword = "hello";
		Console.WriteLine("Case innsensitive: " + Regex.Replace("Hello, hello World!", Regex.Escape(keyword), "<b>$&</b>", RegexOptions.IgnoreCase));
	}
}