You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: On the occasion of Bastille day, I want to travel from Washington to Chicago. Would you book a ticket with in a price limit of 5000?

ASSISTANT: Sure, help me with the travelling dates.

USER: Sure. Travel dates are: 07/13 to 07/15.

ASSISTANT: Can you provide airport codes?

USER: Yes, the airport codes of both locations are DCA-ORD.

ASSISTANT: May I know your name?

USER: William Campbell is my name.

ASSISTANT: There is a flight with fare 100 in airline Southwest. Can I book it?

USER: Sure. Proceed to book.

ASSISTANT: Your ticket is booked in flight number 1004. Happy journey.

USER: Ok, Thank you.

ASSISTANT: Thank you for picking us.