13.RegularExpressionsMoreExercise - Santa's Secret Helper

04. Santa's Secret Helper
After the successful second Christmas, Santa needs to gather information about the behavior of children to plan the presents for next Christmas. He has a secret helper, who is sending him encrypted information. Your task is to decrypt it and create a list of the children who have been good.
You will receive an integer, which represents a key and afterwards some messages, which you must decode by subtracting the key from the value of each character. After the decryption, to be considered a valid match, a message should:
-   Have a name, which starts after '@' and contains only letters from the Latin alphabet
-   Have a behaviour type - "G"(good) or "N"(naughty) and must be surrounded by "!" (exclamation mark).
The order in the message should be: child’s name -> child’s behavior. They can be separated from the others by any character except: '@', '-', '!', ':' and '>'.
You will be receiving message until you are given the “end” command. Afterwards, print the names of the children, who will receive a present, each on a new line.
Input / Constraints
• The first line holds n – the number which you have to subtract from the characters – integer in range [1…100];
• On the next lines, you will be receiving encrypted messages.
Output
Print the names of the children, each on a new line
Examples
Input                       Output    Comments
3                           Kate      We receive three messages and to decrypt them we use the key:
CNdwhamigyenumje$J$         Bobbie    First message has decryption key 3. So we substract from each characters code 3 and we receive:
CEreelh-nmguuejn$J$                   @Kate^jfdvbkrjgb!G!
CVwdq&gnmjkvng$Q$                     @Bobbie*kjdrrbgk!G!
end                                   @Stan#dkjghskd!N!
                                      They are all valid and they contain a child’s name and behavior – G for good and N for naughty.

Input                                     Output          Comments
3                                         Kim             We receive four messages. They are with key 3:
N}eideidmk$'(mnyenmCNlpamnin$J$           Connor          Kzbfabfajh!$%jkvbkj@Kim^jkfk!G!
ddddkkkkmvkvmCFrqqru-nvevek$J$nmgievnge   Valentine       aaaahhhhjshsj@Connor*ksbsbh!G!kjdfbskdb
ppqmkkkmnolmnnCEhq/vkievk$Q$                              mmnjhhhjklijkk@Ben,shfbsh!N!
yyegiivoguCYdohqwlqh/kguimhk$J$                           vvbdffsldr@Valentine,hdrfjeh!G!
end

input                                                Output
4                                                    Bobbie
~lwzjkl~jenlymfDFsffmiCwozwlzjln%K%                  Sammie
0zfjrl}xnrlDWeqqmi/wnznlwzjnn%K%onhfhnf              Lana
;:<lyiljz{onzDPere=;=9<;8=rhknlf%K%                  Samantha
Wonvfkmwzkmpwvzkm'lhjnlDWeqerxle0wlnzj{nz%K%nohwn
DReh}e=<4lhzj1%K%
end

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

public class Program
{
    public static void Main()
    {
          var key = int.Parse(Console.ReadLine());

            var listOfTheChildrenWhoWillReceiveAPresent = new List<string>();

            var encryptedInfo = "";
            while (!(encryptedInfo = Console.ReadLine()).Equals("end"))
            {
                var decryptedInfo = "";
                foreach (var item in encryptedInfo)
                {
                    decryptedInfo += (char)(item - key);
                }
                var patternNameAndType = @"(?<=@)(?<Name>[A-Za-z]+)[^@\-!:>]*!(?<BehaviourType>G|N)(?=!)";
                var matchNameAndBehaviourType = Regex.Matches(decryptedInfo, patternNameAndType);
                foreach (Match item in matchNameAndBehaviourType)
                {
                    var behaviourType = item.Groups["BehaviourType"].Value;
                    if (behaviourType == "G")
                    {
                        var name = item.Groups["Name"].Value;
                        listOfTheChildrenWhoWillReceiveAPresent.Add(name);
                    }
                }
            }
            Console.WriteLine(string.Join("\n", listOfTheChildrenWhoWillReceiveAPresent));
    }
}