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

namespace ConsoleApp222
{
    class Program
    {
        public class User
        {
            public string Sender { get; set; }
            public string ReceivedUser { get; set; }
            public List<string> ReceivedMessages = new List<string>();
        }


        static void Main(string[] args)
        {
            var listRegister = new List<string>();
            var users = new List<User>();
            while (true)
            {
                var text = Console.ReadLine().Split();
                if (text[0] == "exit")
                {
                    break;
                }
                if (text[0] == "register")
                {
                    listRegister.Add(text[1]);
                }
                else
                {
                    var senderUsername = text[0];
                    var recipientUsername = text[2];
                    var content = text[3];
                    if (listRegister.Contains(senderUsername) && listRegister.Contains(recipientUsername))
                    {
                        if (!users.Any(x => x.Sender == senderUsername))
                        {
                            var user = new User();
                            user.Sender = senderUsername;
                            user.ReceivedUser = recipientUsername;
                            user.ReceivedMessages.Add(content);
                            users.Add(user);
                        }
                        else
                        {
                            var index = 0;
                            var br1 = 0;
                            foreach (var item in users)
                            {
                                if (item.Sender == senderUsername && item.ReceivedUser == recipientUsername)
                                {
                                    index = br1;
                                    break;
                                }
                                br1++;
                            }
                            users[index].ReceivedMessages.Add(content);
                        }

                    }
                }
            }
            var text1 = Console.ReadLine().Split();
            var user1 = text1[0];
            var user2 = text1[1];
            var dicUser1 = new Dictionary<string, List<string>>();
            var dicUser2 = new Dictionary<string, List<string>>();
            var br = 0;
            listRegister = listRegister.Distinct().ToList();
            listRegister.RemoveAll(x => (x != user1) && (x != user2));
            foreach (var item in users)
            {
                if (listRegister.Contains(item.Sender) && listRegister.Contains(item.ReceivedUser))
                {
                    br++;
                    var messages = item.ReceivedMessages.ToList();
                    if (br == 1)
                    {
                        dicUser1.Add(item.Sender, new List<string>());
                        for (int i = 0; i < messages.Count; i++)
                        {
                            dicUser1[item.Sender].Add(messages[i]);
                        }
                    }
                    if (br == 2)
                    {
                        dicUser2.Add(item.Sender, new List<string>());
                        for (int i = 0; i < messages.Count; i++)
                        {
                            dicUser2[item.Sender].Add(messages[i]);
                        }
                    }
                }
            }

            if (dicUser1.Count == 0)
            {
                Console.WriteLine("No messages");
            }
            if (dicUser1.Count > 0 && dicUser2.Count > 0)
            {
                foreach (var item in dicUser1)
                {
                    var messages1 = item.Value;
                    foreach (var item1 in dicUser2)
                    {
                        var messages2 = item1.Value;
                        if (messages1.Count == messages2.Count)
                        {
                            for (int i = 0; i < messages1.Count; i++)
                            {
                                Console.WriteLine($"{item.Key}: {messages1[i]}");
                                Console.WriteLine($"{messages2[i]} :{item1.Key}");
                            }
                        }
                        if (messages1.Count > messages2.Count)
                        {
                            for (int i = 0; i < messages2.Count; i++)
                            {
                                Console.WriteLine($"{item.Key}: {messages1[i]}");
                                Console.WriteLine($"{messages2[i]} :{item1.Key}");
                            }
                            for (int i = messages2.Count; i < messages1.Count; i++)
                            {
                                Console.WriteLine($"{item.Key}: {messages1[i]}");
                            }
                        }
                        if (messages2.Count > messages1.Count)
                        {
                            for (int i = 0; i < messages1.Count; i++)
                            {
                                Console.WriteLine($"{item.Key}: {messages1[i]}");
                                Console.WriteLine($"{messages2[i]} :{item1.Key}");
                            }
                            for (int i = messages1.Count; i < messages2.Count; i++)
                            {
                                Console.WriteLine($"{messages2[i]} :{item1.Key}");
                            }
                        }
                    }
                }
            }
            if (dicUser1.Count > 0 && dicUser2.Count == 0)
            {
                foreach (var item in dicUser1)
                {
                    var messages1 = item.Value;
                    for (int i = 0; i < messages1.Count; i++)
                    {
                        Console.WriteLine($"{item.Key}: {messages1[i]}");
                    }
                }
            }
        }
    }
}