Need help writing regular expression

(([0-9A-E][0-9A-F]|[0-9A-F][0-9A-E])\s?)+

((
  [0-9A-E][0-9A-F]      A hex digit excluding "F", followed by a hex digit
  |                     or
  [0-9A-F][0-9A-E]      A hex digit, followed by a hex digit excluding "F"
 )
 \s?                    an optional space
)+                      The whole pattern repeated at least once

string pattern = @"(([0-9A-E][0-9A-F]|[0-9A-F][0-9A-E])\s?)+";
var matches = Regex.Matches(input, pattern);
foreach (var match in matches) {
    Console.WriteLine(match.Value.TrimEnd());
}

string pattern = "[0-9A-E][0-9A-F]|[0-9A-F][0-9A-E]";
var matches = Regex.Matches(input, pattern);
foreach (var match in matches) {
    Console.WriteLine(match.Value);
}