[C# Advanced Exam] Rage Quit

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

class RageQuit
{
    static void Main(string[] args)
    {
        string input = Console.ReadLine().ToUpper();

        StringBuilder result = new StringBuilder();

        string pattern = @".*?[0-9]+";

        Regex regex = new Regex(pattern);

        MatchCollection matches = regex.Matches(input);

        foreach (var match in matches)
        {
            string newMatch = match.ToString();

            int counter = int.Parse(Regex.Match(newMatch, "[0-9]+").ToString());

            newMatch = Regex.Replace(newMatch, @"[0-9]", "");

            for (int i = 0; i < counter; i++)
            {
                result.Append(newMatch);
            }
        }

        Console.WriteLine("Unique symbols used: {0}", CheckUnique(input));
        Console.WriteLine(result);

    }

    public static int CheckUnique(string input)
    {
        input = input.ToUpper();
        Regex rgx = new Regex(@"[0-9]");
        input = rgx.Replace(input, "");

        string unique = new String(input.Distinct().ToArray());
        return unique.Length;
    }
}