using System;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var block = "[0-9a-fA-F]{1,8}";
		var pattern = $@"(?<from>{block})\s*:\s*(?<to>{block})";
		Console.WriteLine(Regex.IsMatch("12345678  :87654321", pattern));
	}
}