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

class Program
{
    static void Main()
    {
        string command = Console.ReadLine();
        List<User> users = new List<User>();

        while (command != "exit")
        {
            string[] split = command.Split();

            if (split[0] == "register")
            {
                RegisteringUser(users, split);
            }
            else
            {
                SendingMessage(users, split);
            }
            command = Console.ReadLine();
        }

        string[] usernames = Console.ReadLine().Split();

        PrintingResults(users, usernames);
    }

    private static void PrintingResults(List<User> users, string[] usernames)
    {
        if (users.Find(u => u.Username == usernames[0]).ReceivedMessages.Count() == 0 && users.Find(u => u.Username == usernames[1]).ReceivedMessages.Count() == 0)
        {
            Console.WriteLine("No messages");
        }
        else
        {
            List<Message> firstUserMessages = users
                .Find(u => u.Username == usernames[1])
                .ReceivedMessages
                .Where(m => m.Sender == usernames[0])
                .ToList();

            List<Message> secondUserMessages = users
                .Find(u => u.Username == usernames[0])
                .ReceivedMessages
                .Where(m => m.Sender == usernames[1])
                .ToList();

            int smallerList = Math.Min(firstUserMessages.Count(), secondUserMessages.Count());
            int biggerList  = Math.Max(firstUserMessages.Count(), secondUserMessages.Count());

            for (int i = 0; i < smallerList; i++)
            {
                Console.WriteLine($"{firstUserMessages[i].Sender}: {firstUserMessages[i].Content}");
                Console.WriteLine($"{secondUserMessages[i].Content} :{secondUserMessages[i].Sender}");
            }

            if (firstUserMessages.Count > secondUserMessages.Count)
            {
                for (int i = smallerList; i < biggerList; i++)
                {
                    Console.WriteLine(($"{firstUserMessages[i].Sender}: {firstUserMessages[i].Content}"));
                }
            }
            else if (secondUserMessages.Count > firstUserMessages.Count)
            {
                for (int i = smallerList; i < biggerList; i++)
                {
                    Console.WriteLine(($"{secondUserMessages[i].Sender}: {secondUserMessages[i].Content}"));
                }
            }

        }
    }

    private static void SendingMessage(List<User> users, string[] split)
    {
        string sender = split[0];
        string reciever = split[2];
        string content = string.Join(" ",split.Skip(3));

        if (users.Where(u => u.Username == sender).Count() > 0 && users.Where(u => u.Username == reciever).Count() > 0)
        {
            Message currentMessage = new Message()
            {
                Content = content,
                Sender = sender
            };
            int recieverIndex = users.IndexOf(users.Find(u => u.Username == reciever));

            users[recieverIndex].ReceivedMessages.Add(currentMessage);
        }
    }
    private static void RegisteringUser(List<User> users, string[] split)
    {
        if (users.Where(u => u.Username == split[1]).Count() == 0)
        {
            users.Add(new User() { Username = split[1], ReceivedMessages = new List<Message>() });
        }
    }
}
class User
{
    public string Username { get; set; }
    public List<Message> ReceivedMessages { get; set; }
}

class Message
{
    public string Content { get; set; }
    public string Sender { get; set; }
}