using System;

using System.Text.RegularExpressions;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var list = ThreeCharacterIncrementor("ZZZ34", 1000);

        foreach(var seq in list) 

        {

            Console.WriteLine(seq); 

        }

    }

    public static List<string> ThreeCharacterIncrementor(string lastIndice, int numberOfLabels)

    {

        var newSequence = new List<string>();

        //Step 0: Parse lastIndice 

        var regexPattern = "([A-Z]+)";

        var regexResults = Regex.Split(lastIndice, regexPattern);

        var characters = regexResults[1].ToString();

        var numbers = Convert.ToInt32(regexResults[2]);

        var charactersArray = characters.ToCharArray();

        var firstCharacter = charactersArray[0];

        var secondCharacter = charactersArray[1];

        var thirdCharacter = charactersArray[2];

        //Step 1: Increment through the last indice

        int secondCharIndex = 1;

        int firstCharIndex = 1;

        var newSecondChar = secondCharacter;

        var newFirstChar = firstCharacter;

        var thirdCharStartIndice = Convert.ToInt32(firstCharacter) - 65;

        var secondCharStartIndice = Convert.ToInt32(secondCharacter) - 65;

        var firstCharStartIndice = Convert.ToInt32(thirdCharacter) - 65;

        for(int i = 1; i <= numberOfLabels; i++)

        {

            //Step 1.1: Increment the second character

            var thirdCharIndice = (i + thirdCharStartIndice) % 26; 

            var thirdCharAsciiValue = 65 + thirdCharIndice;

            var newThirdChar = Convert.ToChar(thirdCharAsciiValue);

            //Step 1.2: Increment the second character and third character

            if(thirdCharIndice == 0)

            {

                var secondCharIndice = (secondCharIndex + secondCharStartIndice) % 26;

                var secondCharAsciiValue = 65 + secondCharIndice;

                newSecondChar = Convert.ToChar(secondCharAsciiValue);

                if(secondCharIndice == 0 && thirdCharIndice == 0)

                {

                    var firstCharIndice = (firstCharIndex + firstCharStartIndice) % 26;

                    var firstCharAsciiValue = 65 + firstCharIndice;

                    newFirstChar = Convert.ToChar(firstCharAsciiValue);

                    firstCharIndex++;

                }

                secondCharIndex++;

            }

            //Step 1.3: Increment the number observed

            numbers = numbers + 1;

            //Step 1.4: Add new indice to sequence 

            newSequence.Add(newFirstChar.ToString() + newSecondChar.ToString() + newThirdChar.ToString() + numbers.ToString());

        }

        return newSequence;

    }

}