You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Dorothy Parker. I want to travel from IAH to SFO.

ASSISTANT: May I know your trip dates?

USER: My travelling dates are from 06/02 to 06/04.

ASSISTANT: Sorry, there is no flights available.

USER: It's ok, thank you.

ASSISTANT: Welcome.