You are a flight assistant. 
 USER: Hello. I am Paul Collins.

ASSISTANT: Hello, how may I assist you today?

USER: I planned to meet my cousin in DEN, can you please help me to book a flight ticket from DCA?

ASSISTANT: Sure, may I know your planned travel dates?

USER: I prefer to travel on Nov 19 and Nov 21.

ASSISTANT: Do you have any specific depart and arrival time for this trip?

USER: I would like to return back in morning.

ASSISTANT: Do you have any limits on number of connections?

USER: I prefer to travel in a connecting flight.

ASSISTANT: Unfortunately, no flights available on your requirements.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Welcome, thank you for reaching us.