You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Patrick Robinson. I am planning to visit Pier 39 in SFO. Can you book a ticket from DFW?

ASSISTANT: Sure. May I know your preferable dates?

USER: I am planning to start my journey on 04/03 and return will be on 04/05.

ASSISTANT: Sorry Patrick, There is no flight available.

USER: It's fine. Anyway, thank you for your help.

ASSISTANT: Most welcome.