using System;
using System.Collections.Generic;

namespace SoftUniParking
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            Dictionary<string, string> dict = new Dictionary<string, string>();

            for (int i = 0; i < n; i++)
            {
                string[] command = Console.ReadLine().Split();
                if (command[0] == "register")
                {
                    RegisterUser(dict, command[1], command[2]);

                }
                else if (command[0] == "unregister")
                {
                    if (dict.ContainsKey(command[1]))
                    {
                        dict.Remove(command[1]);
                        Console.WriteLine($"{command[1]} unregistered successfully");
                    }
                    else
                    {
                        Console.WriteLine($"ERROR: user {command[1]} not found");
                    }

                }
            }
            foreach (var item in dict)
            {
                Console.WriteLine($"{item.Key} => {item.Value}");
            }
        }

        static void RegisterUser(Dictionary<string, string> dict, string name, string plate)
        {
            if (!dict.ContainsKey(name))
            {
                dict.Add(name, plate);
                Console.WriteLine($"{name} registered {plate} successfully");
            }
            else
            {
                Console.WriteLine($"ERROR: already registered with plate number {dict.GetValueOrDefault(name)}");
            }
        }
    }
}