You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I'm Larry King, I want to book a ticket. Can you help me out?

ASSISTANT: Sure, it's my pleasure to help you. Can you please provide the airport codes?

USER: They are LAX and DFW.

ASSISTANT: May I know your travelling dates?

USER: It's from 07/15 to 07/17.

ASSISTANT: OK, wait for a minute.

USER: OK.

ASSISTANT: Sorry for the inconvenience, there is no flight available.

USER: That's OK. Thank you for your time.

ASSISTANT: Thank you.Have a great day.