You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Please help me in booking a flight ticket from ORD to LAS.

ASSISTANT: Sure, can you share your trip dates?

USER: Aug, 7 and Aug, 9 are my trip dates.

ASSISTANT: Do you have any preferences?

USER: I need to travel in connecting flight with normal cost airlines.

ASSISTANT: May I know your name?

USER: Alexander Miller here.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.