string input = "";
            string[] commands;
            var phonebook = new SortedDictionary<string, string>();
            while (input != "END")
            {
                input = Console.ReadLine();
                commands = input.Split();
                if (commands[0] == "A")
                {
                    if (phonebook.ContainsKey(commands[1]))
                    {
                        phonebook[commands[1]] = commands[2];
                    }
                    else
                    {
                        phonebook.Add(commands[1], commands[2]);
                    }
                }
                else if (commands[0] == "S")
                {
                    if (phonebook.ContainsKey(commands[1]))
                    {
                        Console.WriteLine(commands[1] + " -> " + phonebook[commands[1]]);
                    }
                    else
                    {
                        Console.WriteLine("Contact {0} does not exist.", commands[1]);
                    }
                }
                else if (commands[0] == "ListAll") {
                    foreach (var item in phonebook)
                    {
                        Console.WriteLine(item.Key + " -> " + item.Value);
                    }
                }
            }