Fancy Barcodes

using System;
using System.Text.RegularExpressions;

class Program
{
    static void Main()
    {
        string regex1 = @"\A\@#+[A-Z]([A-Za-z\d]{4,})[A-Z]\@#+\Z";
        string regex2 = @"\d";
        int numberOfProducts = int.Parse(Console.ReadLine());
        for (int i = 0; i < numberOfProducts; i++)
        {
            string entry = Console.ReadLine();
            Match match = Regex.Match(entry, regex1);
            if (match.Success)
            {
                string rawData = match.Groups[1].Value;
                MatchCollection digits = Regex.Matches(rawData, regex2);
                string productGroup = string.Empty;
                if (digits.Count > 0)
                {
                    foreach (Match digit in digits)
                        productGroup += digit;
                }
                else
                {
                    productGroup = "00";
                }
                Console.WriteLine($"Product group: {productGroup}");
            }
            else
                Console.WriteLine("Invalid barcode");
        }
    }
}