You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you?

USER: Eric Green here. I like to attend a birthday party, so can you help me in booking a ticket from SFO to HOU?

ASSISTANT: May I know your travelling dates?

USER: My travelling dates are from 08/31 to 09/02.

ASSISTANT: Sorry Eric, there is no flight with your requirements.

USER: That's fine.

ASSISTANT: Thank you for choosing us.

USER: You are welcome.