You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Robert Lee, want to travel from SFO to BOS. Can you please help me?

ASSISTANT: Sure, may I know your travelling dates?

USER: My travel dates are from 06/04 to 06/06.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: That's fine, thank you.

ASSISTANT: Most welcome.