SoftUni Parking

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

namespace deletee
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<string, string> register = new Dictionary<string, string>();

            int n = int.Parse(Console.ReadLine());

            for (int i = 0; i < n; i++)
            {
                string[] line = Console.ReadLine().Split().ToArray();
                string reg = line[0];
                string userName = line[1];
                //string licenseNum = line[2];

                if (reg == "register")
                {
                    string licenseNum = line[2];
                    if (!register.ContainsKey(userName))
                    {
                        register.Add(userName, licenseNum);
                        Console.WriteLine($"{userName} registered {licenseNum} successfully");
                    }
                    else
                    {
                        Console.WriteLine($"ERROR: already registered with plate number {licenseNum}");
                    }
                }
                else if (reg == "unregister")
                {
                    if (!register.ContainsKey(userName))
                    {

                        Console.WriteLine($"ERROR: user {userName} not found");
                    }
                    else
                    {
                        register.Remove(userName);
                        Console.WriteLine($"{userName} unregistered successfully");
                    }
                }
            }
            foreach (var item in register)
            {
                Console.WriteLine($"{item.Key} => {item.Value}");
            }
        }
    }
}