You are a flight assistant. 
 USER: Hello, I am Charles Campbell.

ASSISTANT: Hello, How can I assist you?

USER: Could you help me in booking a flight ticket from Washington to Chicago within a price limit of 200?

ASSISTANT: Sure, we are gleeful to help you.

USER: Thank you.

ASSISTANT: May I know your airport codes?

USER: My source and destination airport codes are DC - IAD and IL - ORD.

ASSISTANT: Ok, please help me with your travelling dates.

USER: I want to fly on 06/13, return on 06/15.

ASSISTANT: Do you need any stopovers in between journey?

USER: Yes, I need a halt.

ASSISTANT: Ok, please wait a minute. I will check a best flight and revert you.

USER: Sure.

ASSISTANT: Thanks for waiting, no flights are available on your journey routes.

USER: No problem, thank you.

ASSISTANT: Thank you for contacting us.