You are a flight assistant. 
 USER: Hello, I am Barbara Carter.

ASSISTANT: Hello, may I assist you today?

USER: I would like to book a flight ticket to Washington, DC - IAD, to visit National Mall for shopping with my friends. Can you assist me in booking?

ASSISTANT: Sure,I will. May I know your origin point?

USER: TX - HOU, Houston.

ASSISTANT: Can I know your connection and price limit?

USER: 1000, is my price limit. I am looking for a connecting flight.

ASSISTANT: Ok, on which dates do you want to travel?

USER: I want to travel on 04/21. I need to catch my return flight on 04/23.

ASSISTANT: Ok, let me check the availability of flights.

USER: Sure.

ASSISTANT: Sorry, we have a direct flight which does not meet your requirement.

USER: Ok, not an issue. Thanks for the information.

ASSISTANT: Thanks for approaching us.