You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Justin Williams.

ASSISTANT: How may I aid you?

USER: Please book a flight ticket from IAH to SFO, as I meet my family at San Francisco.

ASSISTANT: Sure, I am here to help you out. May I know your travelling dates please?

USER: My travelling dates are Dec, 24 and Dec, 26.

ASSISTANT: Do you have any airline preferences?

USER: I am comfortable with any airline but make sure that my return time must be at afternoon.

ASSISTANT: Do you need any halt ?

USER: Yes, I need a halt.

ASSISTANT: Justin Williams, there are no flights available in your route.

USER: It's OK, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for the information.