Rage Quit [Hristo]

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

namespace Task_3
{
    class Program
    {
        static void Main(string[] args)
        {
            var input = Console.ReadLine();
            //string letterCounter = "";
            //Dictionary<string, int> dictLetterDigit = new Dictionary<string, int>();

            string pattern = "([^0-9]+[0-9]+)";
            Regex regex = new Regex(pattern);
            MatchCollection m = regex.Matches(input);
            StringBuilder result = new StringBuilder();
            var uniqueSymbols = new HashSet<char>();
            //int digit = 0;

            foreach (var word in m)
            {
                //letters = string.Empty;
                string wordToString = word.ToString();


                int index = 0;
                string number = String.Empty;
                string symbols = String.Empty;

                while(index < wordToString.Length)
                {
                    if (wordToString[index] >= '0' && wordToString[index] <= '9')
                    {
                        number += wordToString[index];
                    }
                    else
                    {
                        symbols += wordToString[index];
                    }
                    index++;
                }

                symbols = symbols.ToUpper();
                //Console.WriteLine("SYMBOLS: {0}", symbols);
                //Console.WriteLine("NUMBER: {0}", number);

                for (int i = 0; i < int.Parse(number); i++)
                {
                    result.Append(symbols);

                    foreach (var symbol in symbols)
                    {
                        uniqueSymbols.Add(symbol);
                    }
                }


               // string wordpattern = "([^0-9])";

               // string[] bu = Regex.Split(word.ToString(), wordpattern);

               // Console.WriteLine("Bu: " + String.Join(" ", bu));
                /*foreach (var letter in bu)
                {

                    if (int.TryParse(letter, out digit))
                    {
                        digit = int.Parse(letter);
                        if (digit <= 0)
                        {
                            continue;
                        }
                    }
                    else
                    {
                        letters += letter.ToString().ToUpper();
                    }
                }
                foreach (var g in letters)
                {
                    if (!letterCounter.Contains(g) && !String.IsNullOrWhiteSpace(g.ToString()))
                    {
                        letterCounter += g;
                    }
                }*/
                //dictLetterDigit.Add(letters, digit);
            }
            //Console.WriteLine(resylt);
            Console.WriteLine("Unique symbols used: {0}", uniqueSymbols.Count());
            Console.WriteLine(result);
            /*foreach (var blabla in dictLetterDigit)
            {
                for (int i = 0; i < blabla.Value; i++)
                {
                    Console.Write(blabla.Key);
                }
            }*/
        }
    }
}