You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Brian Harris here. I have a seminar in Las Vegas.Can you please help me for booking a ticket?

ASSISTANT: Sure, which airport you want leave?

USER: My airport codes are from DC-IAD to NV-LAS.

ASSISTANT: On which dates you want to travel?

USER: My departure date is 07/03 and return date is 07/05. Make sure my connections limit is 0. My price limit is 200.

ASSISTANT: I am really sorry for to tell you, I cannot find any flight with 0 connection.

USER: Ok, thank you for the information.

ASSISTANT: Thank you.