You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Laura Clark here. Could you book my ticket in a direct flight?

ASSISTANT: Sure, may I know your travelling dates of journey?

USER: My trip dates are Oct 6 and Oct 8.

ASSISTANT: Ok, may I know your airports codes of journey?

USER: I want to travel from SFO to DFW.

ASSISTANT: May I know your class preference please?

USER: I have no class preference. I want to return in the evening.

ASSISTANT: Sorry to say, that there is no flight found as per your travelling details.

USER: No problem, thank you.

ASSISTANT: You are welcome.