You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you now?

USER: Can you please book a ticket from DEN to SFO to participate in Death Valley Adventure?

ASSISTANT: May I know your journey dates?

USER: My journey dates are Apr 21 and Apr 23.

ASSISTANT: May I know your name please?

USER: Sure, I am James King.

ASSISTANT: Do you need a connecting flight?

USER: Yes.

ASSISTANT: Do you have any other requirements?

USER: I prefer normal-cost airline.

ASSISTANT: Sorry to say, there is no flight available for your journey.

USER: Ok, Thank you for your service.

ASSISTANT: Thank you for choosing our services.