using System;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
            string text = "Hello world :low this \"but not this\" or 'this'";
            text = Regex.Replace(text, @":\w+|""[^""]*""|'[^']*'|(.)",
                                 match => match.Groups[1].Success ? match.Groups[1].Value.ToUpper() : match.Value);
            Console.WriteLine(text);
	}
}