You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, what can I do for you?

USER: Rachel Collins here. I need a direct flight to reach Las Vegas as it is a urgent case, so please help me with booking a flight ticket on 07/18 and 07/20.

ASSISTANT: Ok, I can help you out.

USER: Thank you.

ASSISTANT: May I know your dates of travel?

USER: I have already provided above.

ASSISTANT: Sorry, I need airport codes?

USER: I would like to depart from JFK and land at LAS.

ASSISTANT: No flights are available with your request. Thanks for reaching us, have a nice day.

USER: No issue, thank you.