You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Stephanie Carter.

ASSISTANT: I hope you are fine, how can I help you now?

USER: I would like to celebrate my mother birthday at Houston, please help me out in booking a ticket.

ASSISTANT: That's nice, I will help you in booking the flight ticket. May I know the preferable dates of your journey?

USER: My preferable dates are from 09/09 to 09/11.

ASSISTANT: Ok, can you please mention the take off and landing airport codes of your journey?

USER: My airport codes are from DCA and IAH.

ASSISTANT: Thank you for your information, please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry for the inconvenience, there are no flights found on your requirement.

USER: Ok, no problem, thank you for your information.

ASSISTANT: Do you have any other plans to travel?

USER: No, thank you.

ASSISTANT: Thank you for approaching us, have a nice day.