You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Nicholas Garcia here. Could you help me in booking a ticket from PHL to HOU.

ASSISTANT: Let me know your travelling dates.

USER: My planned travel dates are as follows Sept 16 and Sept 18.

ASSISTANT: Is there any connection limit?

USER: I would like to board a direct flight.

ASSISTANT: Do you have any class preference?

USER: No, I have no preferences.

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