You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am Dorothy Parker. I would like to meet my friend at Las Vegas. Can you please help me to book a flight ticket from ORD to LAS?

ASSISTANT: Sure, can you please mention your journey dates?

USER: My planned journey dates are Aug 29 and Aug 31.

ASSISTANT: Do you have any other specifications?

USER: My depart time should be evening.

ASSISTANT: Thank you for your information, non of the airlines is providing a flight in the evening time to reserve a flight ticket.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: You are most welcome and thank you for reaching us.