Star enigma

using System;
using System.Collections.Generic;
using System.Linq;

namespace StarEnigma_03_18
{
    class Program
    {
        static void Main(string[] args)
        {
            int numberOfMessages = int.Parse(Console.ReadLine());

            List<string> attackedPlanets = new List<string>();
            List<string> destroyedPlanets = new List<string>();

            for (int currentMessage = 1; currentMessage <= numberOfMessages; currentMessage++)
            {
                string message = Console.ReadLine();

                string temp = message.ToLower();
                int count = 0;

                for (int index = 0; index < temp.Length; index++)
                {
                    char symbol = temp[index];

                    if (symbol == 's' || symbol == 't' || symbol == 'a' || symbol == 'r')
                    {
                        count++;
                    }
                }

                string decoded = string.Empty;

                for (int index = 0; index < message.Length; index++)
                {
                    decoded += (char)(message[index] - count);
                }

                int indexOfVerbatim = decoded.IndexOf('@');
                int indexOfPoints = decoded.IndexOf(':');
                int indexOfExclamation = decoded.IndexOf('!');
                int indexOfBigger = decoded.IndexOf('>');

                if (indexOfVerbatim < 0 || indexOfPoints < 0 || indexOfExclamation < 0 || indexOfBigger < 0)
                {
                    continue;
                }

                if (indexOfVerbatim > indexOfPoints || indexOfPoints > indexOfExclamation || indexOfExclamation + 2 > indexOfBigger)
                {
                    continue;
                }

                if (Char.IsDigit(decoded[indexOfPoints + 1]) == false
                    || Char.IsDigit(decoded[indexOfBigger + 1]) == false)
                {
                    continue;
                }

                string planetName = null;

                for (int i = indexOfVerbatim + 1; i < indexOfPoints; i++)
                {
                    char symbolOfPlanet = decoded[i];

                    if ((symbolOfPlanet >= 'A' && symbolOfPlanet <= 'Z')
                        || (symbolOfPlanet >= 'a' && symbolOfPlanet <= 'z'))
                    {
                        planetName += symbolOfPlanet;
                    }
                    else
                    {
                        break;
                    }
                }

                char attackType = decoded[indexOfExclamation + 1];

                if (planetName != null && decoded[indexOfExclamation + 2] == '!')
                {
                    if (attackType == 'A')
                    {
                        attackedPlanets.Add(planetName);
                    }
                    else if (attackType == 'D')
                    {
                        destroyedPlanets.Add(planetName);
                    }
                }
            }

            attackedPlanets = attackedPlanets.OrderBy(p => p).ToList();
            destroyedPlanets = destroyedPlanets.OrderBy(p => p).ToList();

            Console.WriteLine($"Attacked planets: {attackedPlanets.Count}");

            foreach (string planet in attackedPlanets)
            {
                Console.WriteLine($"-> {planet}");
            }

            Console.WriteLine($"Destroyed planets: {destroyedPlanets.Count}");

            foreach (string planet in destroyedPlanets)
            {
                Console.WriteLine($"-> {planet}");
            }
        }
    }
}