Sample Exam - Genome Decoder

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace _01.GenomeDecoder
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] dimensions = Console.ReadLine().Split(' ');
            int line = int.Parse(dimensions[0]);
            int space = int.Parse(dimensions[1]);
            string genome = Console.ReadLine();
            string pattern = @"(\d*)(\w)";
            List<int> count = new List<int>();
            List<string> letter = new List<string>();
            bool finished = false;

            foreach (Match match in Regex.Matches(genome,pattern))
            {
                int countLetter=0;
                if (!int.TryParse(match.Groups[1].Value, out countLetter))
                {
                    countLetter = 1;
                }
                string currentLetter = match.Groups[2].Value;
                count.Add(countLetter);
                letter.Add(currentLetter);

            }

            int printedLetter = 0;
            int lineCount = 1;
            int totalSum = count.Sum();
            int totalLines = totalSum / line;
            if (totalSum%line != 0)
            {
                totalLines++;
            }
            int padding = totalLines.ToString().Length;
            string realPadding = "{0," + padding + "} ";
            StringBuilder output = new StringBuilder();
            string format = String.Format(realPadding, lineCount);

            output.Append(format);
            realPadding = "\n" + realPadding;
            lineCount++;
            int length = count.Count;

            for (int i = 0; i < length; i++)
            {
                int letterLength = count[i];
                for (int j = 0; j < letterLength; j++)
                {
                    output.Append(letter[i]);
                    printedLetter++;
                    if (i == count.Count - 1 && j == count[i] - 1)
                    {
                        finished = true;

                    }
                    if(printedLetter%line == 0 && finished == false)
                    {
                            output.Append(String.Format(realPadding, lineCount));

                        lineCount++;
                        printedLetter = 0;
                    }
                    else if (printedLetter % space == 0 && finished == false)
                    {
                        output.Append(' ');
                    }

                }

            }
            Console.WriteLine(output);
        }
    }
}