You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am William Gonzalez. Can you book a ticket from PHL to EWR?

ASSISTANT: Let me know your travel dates.

USER: My travelling dates are on Dec 22 and Dec 24.

ASSISTANT: Do you have any preference?

USER: My depart time is morning. I need a connecting flight.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thanks.