if (isset($_SESSION['return_flight_departure_city'])) $return_flight_departure_city = $_SESSION['return_flight_departure_city'];
if (isset($_SESSION['return_flight_arrival_city'])) $return_flight_arrival_city = $_SESSION['return_flight_arrival_city'];
if (isset($_SESSION['return_flight_departure_date'])) {
if (isset($_SESSION['return_flight_departure_city'])) $return_flight_departure_city = $_SESSION['return_flight_departure_city'];
if (isset($_SESSION['return_flight_arrival_city'])) $return_flight_arrival_city = $_SESSION['return_flight_arrival_city'];
if (isset($_SESSION['return_flight_departure_date'])) {