using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

         var input = "x = ABZZT - AC050, AB055, AB060-AB099";

​

            var valuePart = input.Split('=')[1]; //The part after the `=`

​

            //Based on [Dervis answer](https://stackoverflow.com/a/63808466/6560478)

            var ranges = valuePart.Split(',')

                                  .Select(x => {

                                      var range = x.Split('-')

                                                    .Select(x=> x.Trim())

                                                    .ToList();

​

                                      if (range.Count() > 1)

                                          return RangeLong(BaseToLong(range[0]), BaseToLong(range[1]) - BaseToLong(range[0]) + 1);

​

                                      return RangeLong(BaseToLong(range[0]), 1);

                                  });

​

            var result = ranges.SelectMany(x => x.Select(y=> LongToBase(y))).ToList();

            result.Dump();

    }

        //Based on https://referencesource.microsoft.com/#System.Core/System/Linq/Enumerable.cs,1271

        static IEnumerable<long> RangeLong(long start, long count)

        {

            for (int i = 0; i < count; i++) yield return start + i;

        }

​

​

        //Based on https://stackoverflow.com/questions/923771/quickest-way-to-convert-a-base-10-number-to-any-base-in-net

        private static readonly char[] BaseChars =

         "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();

        private static readonly Dictionary<char, int> CharValues = BaseChars

                   .Select((c, i) => new { Char = c, Index = i })

                   .ToDictionary(c => c.Char, c => c.Index);

​

        public static string LongToBase(long value)

        {

            long targetBase = BaseChars.Length;

            // Determine exact number of characters to use.

            char[] buffer = new char[Math.Max(

                       (int)Math.Ceiling(Math.Log(value + 1, targetBase)), 1)];

​

            var i = buffer.Length;

            do

            {

                buffer[--i] = BaseChars[value % targetBase];

                value = value / targetBase;

            }

            while (value > 0);

​

            return new string(buffer, i, buffer.Length - i);

        }

​

        public static long BaseToLong(string number)

        {

            char[] chrs = number.ToCharArray();

            int m = chrs.Length - 1;

            int n = BaseChars.Length, x;

            long result = 0;

            for (int i = 0; i < chrs.Length; i++)

            {

                x = CharValues[chrs[i]];

                result += x * (long)Math.Pow(n, m--);

            }

            return result;

        }

}