You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am Anna Phillips here. I want to book my flight ticket from LAS to JFK.

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

USER: Ok, my preferable travelling dates are from 04/29 to 05/01.

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

USER: Ok, no problem. Thank you for your help.

ASSISTANT: You are welcome always.