static void Main()
{
RentSystem rentsys = new RentSystem();
IRent example = rentsys;
IVehicleService example1 = new VehicleServiceManager(rentsys);
ICustomer example2 = new CustomerManager(rentsys);
example.AddCar(0, 100, "BMW", 1000, 10);
example.AddCar(1, 200, "KIA", 0, 20);
example.AddCar(2, 999, "local", 0, 1000);
example.AddContract(new DateTime(2020, 12, 31), new DateTime(1999, 01, 01));
example.AddCarToContract(1, 0);
example.RemoveCarFromContract(1, 0);
example.RemoveCar(2);
//example.AddCustomer(true, "John Dyr", 10, "173 Bui Vien"); //cái này PHẢI BỊ LỖI khi gỡ dấu //
example2.AddCustomer(true, "John Dyr", 10, "173 Bui Vien");
example2.AddCustomer(false, "Odinson", 59, "53 Wall Str.");
example2.AddCustomer(true, "Imma die soon", 99, "Unknown");
example2.RemoveCustomer(2);
example2.AddCustomerToContract(1, 0);
example2.AddCustomerToContract(1, 0);
example2.RemoveCustomerFromContract(1, 0);
example2.AddCustomerToContract(1, 0);
}