Rage Quit

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

namespace _03.RageQuit
{
    class RageQuit
    {
        static void Main()
        {
            string text = Console.ReadLine();
            //var pairs = new Dictionary<string, int>();
            var uniqueSymbols = new HashSet<char>();
            StringBuilder result = new StringBuilder();

            Regex pattern = new Regex(@"(?<string>[^0-9]+)(?<number>[0-9]+)");
            MatchCollection matches = pattern.Matches(text);

            foreach (Match match in matches)
            {
                string str = match.Groups["string"].ToString();
                str = str.ToUpper();
                int number = int.Parse(match.Groups["number"].ToString());

                for (int cnt = 0; cnt < number; cnt++)
                {
                    result.Append(str);

                    foreach (var symbol in str)
                    {
                        uniqueSymbols.Add(symbol);
                    }
                }
            }
            Console.WriteLine("Unique symbols used: {0}", uniqueSymbols.Count());
            Console.WriteLine(result);
        }
    }
}