2. Rage Quit

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

namespace _2._Rage_Quit
{
    class Program
    {
        static void Main(string[] args)
        {
            string text = Console.ReadLine().ToUpper();

            var strBuilder = new StringBuilder();

            List<char> uniqueSymbols = new List<char>();

            MatchCollection allSymbolsWithoutDigits = Regex.Matches(text, @"\D");

            foreach (Match symbol in allSymbolsWithoutDigits)
            {
                strBuilder.Append(symbol.Value);
            }

            for (int i = 0; i < strBuilder.Length; i++)
            {
                if (!uniqueSymbols.Contains(strBuilder[i]))
                {
                    uniqueSymbols.Add(strBuilder[i]);
                }
            }

            Console.WriteLine($"Unique symbols used: {uniqueSymbols.Count}");

            strBuilder = new StringBuilder();

            var dataWithoutDigits = Regex.Matches(text, @"(?<symbols>\D+)(?<count>\d+)");

            foreach (Match match in dataWithoutDigits)
            {
                string currentSymbolGroup = match.Groups["symbols"].Value;
                int countOfRepeats = int.Parse(match.Groups["count"].Value);

                for (int i = 0; i < countOfRepeats; i++)
                {
                    strBuilder.Append(currentSymbolGroup);
                }

            }

            Console.WriteLine(strBuilder);

        }
    }
}