You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Amanda Collins. Can you please book me a flight ticket from LAS to DFW?

ASSISTANT: Nice to meet you, Amanda. Sure, may I know your trip dates?

USER: My travelling dates are from 05/21 to 05/23. My ticket cost should be within the range of 500.

ASSISTANT: Sorry for inconvenience, there is no flight available with these location.

USER: It's ok. Thank you.

ASSISTANT: Most welcome.