You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Dennis Hall. I want to book a direct flight from DEN to meet my friend, can you help me with booking?

ASSISTANT: Let me know your travel dates.

USER: My travel dates are Mar 27 and Mar 29.

ASSISTANT: Do you have any preference?

USER: My return time  is evening.

ASSISTANT: Can I know your destination airport code?

USER: My destination airport code is SFO.

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

USER: Ok, no issues.

ASSISTANT: Thank you.

USER: Thank you for your help.