You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Kathleen Robinson here.

ASSISTANT: Kathleen Robinson, how can I help you?

USER: I want to attend a seminar on machine learning, so please book my ticket from SFO to DEN.

ASSISTANT: May I know the trip dates?

USER: My itinerary dates are Aug 11 and Aug 13.

ASSISTANT: Is there any time concern?

USER: I want to return in the evening.

ASSISTANT: May I know the connection limit?

USER: I need a connecting flight.

ASSISTANT: give me a moment. Sorry to inform that there are no flights with your requirements.

USER: No problem, thank you.

ASSISTANT: Thank you for reaching us.