Emoji Detector

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

class Program
{
    static void Main()
    {
        string input = Console.ReadLine();
        MatchCollection digits = Regex.Matches(input, @"\d");
        MatchCollection emojis = Regex.Matches(input, @"([:*])\1[A-Z][a-z]{2,}\1\1");

        BigInteger coolThreshold = new BigInteger(1);
        foreach (Match digit in digits)
            coolThreshold *= int.Parse(digit.Value);

        List<string> coolEmojis = new List<string>();
        foreach (Match emoji in emojis)
        {
            string emojiString = emoji.Value;
            int emojiValue = 0;
            for (int i = 0; i < emoji.Value.Length; i++)
            {
                if (char.IsLetter(emojiString[i]))
                    emojiValue += (int)emojiString[i];
            }
            if (emojiValue > coolThreshold)
                coolEmojis.Add(emojiString);
        }

        Console.WriteLine($"Cool threshold: {coolThreshold}");
        Console.WriteLine($"{emojis.Count} emojis found in the text. The cool ones are:");
        Console.WriteLine(String.Join("\n", coolEmojis));
    }
}