You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: David Hill here.

ASSISTANT: How may I aid you?

USER: I want to book a flight ticket on the route from LAS - IAD to meet my mother, can you help me?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Can I know your preferable travel dates to proceed further?

USER: My travelling dates will be from 12/26 to 12/18.

ASSISTANT: Ok, please be on hold, let me check for the flight availability.

USER: Ok, please check for the flights with price of 1000.

ASSISTANT: Sorry to say you that, there are no flights available in this route matching to your details.

USER: Oh! That's fine, thank you for checking.

ASSISTANT: Welcome and thank you for choosing our agency.

USER: You are welcome.