You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Please book a flight ticket from DCA to SFO.

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

USER: My trip dates are 07/27 and 07/29.

ASSISTANT: May I know your connection limit?

USER: I need a connecting flight to travel.

ASSISTANT: Do you need any other preference?

USER: Yes, I prefer to depart in morning.

ASSISTANT: Can I know your name please?

USER: I am Richard Wilson.

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

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for contacting us.