You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I am Andrew White. I want to book a flight ticket from IAD to PHL. Could you help me in booking?

ASSISTANT: Sure, I am here to help you in booking. Can you please share your travel dates?

USER: My travelling dates are from Dec 29-31.

ASSISTANT: Do you have any airline preference?

USER: No, I don't have any airline preference.

ASSISTANT: May I know your departure time and return time?

USER: My depart time should be in the morning.

ASSISTANT: Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, no flights are available on your preferable travel dates.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for opting us, have a nice day.