You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: I am William Clark. Can you help me in booking from DCA to HOU?

ASSISTANT: Sure, let me know your travel dates please?

USER: My travelling dates are from May 8 to May 10.

ASSISTANT: Do you have any specific depart and arrival timings?

USER: I want to depart in the evening and return in the afternoon.

ASSISTANT: May I know your connection limit?

USER: I need a connecting flight.

ASSISTANT: Ok, is there any class preference?

USER: No.

ASSISTANT: Do you have any airline preference?

USER: I am comfortable with any airline.

ASSISTANT: Sorry to inform you that there are no flight services available on your given details.

USER: Ok, No issues. Thank you.

ASSISTANT: Thanks for reaching us, have a nice day.