You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Can you please help me to reserve a flight ticket from Washington to Houston?

ASSISTANT: Sure, may I know the planned travel dates to check for the flight availability?

USER: Thank you. My planned travel dates are Nov 21 and Nov 23.

ASSISTANT: Please provide me the airport codes.

USER: I want to start my journey from the airport DCA to reach HOU airport.

ASSISTANT: Do you have any specification in connection limit?

USER: Yes, I am looking for a direct flight as I don't like any delays in between my journey.

ASSISTANT: Please provide me the name.

USER: Sure, I am Barbara White.

ASSISTANT: Do you have any class or airline preference for this journey?

USER: Yes, I have a preference about the class that should be an economy type.

ASSISTANT: Sorry, there are no flights are available for your desired intent.

USER: Oh! It is so sad to hear. Anyways thank you for your time.

ASSISTANT: Thank you for reaching us.