Star Enigma

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

class StarEnigma
{
    static void Main(string[] args)
    {
        int messagesCount = int.Parse(Console.ReadLine());

        string star = @"[sStTaArR]";
        string messagePattern = @"@(?<planet>[a-zA-Z]+)[^@\-!:>]*:(?<population>\d+)[^@\-!:>]*!(?<attackType>[AD])![^@\-!:>]*->(?<soldiers>\d+)";
        var planets = new SortedDictionary<string, List<string>>();

        planets.Add("A", new List<string>());
        planets.Add("D", new List<string>());

        for (int currentMessage = 0; currentMessage < messagesCount; currentMessage++)
        {
            string message = Console.ReadLine();

            int key = 0;
            StringBuilder newMessage = new StringBuilder();

            foreach (Match starMatch in Regex.Matches(message, star))
            {
                key++;
            }

            foreach (char symbol in message)
            {
                newMessage.Append(Convert.ToChar(symbol - key));
            }

            string decodedMessage = newMessage.ToString();
            Match validMessage = Regex.Match(decodedMessage, messagePattern);

            if (validMessage.Success)
            {
                string attackType = validMessage.Groups["attackType"].Value;
                string planet = validMessage.Groups["planet"].Value;

                planets[attackType].Add(planet);
            }
        }

        foreach (var pair in planets)
        {
            if (pair.Key == "A")
            {
                Console.WriteLine($"Attacked planets: {pair.Value.Count}");
            }
            else
            {
                Console.WriteLine($"Destroyed planets: {pair.Value.Count}");
            }

            foreach (string planet in pair.Value.OrderBy(p => p))
            {
                Console.WriteLine($"-> {planet}");
            }
        }
    }
}