You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am planning to spend my free time with my parents who is staying at DCA, can you help me with booking a connecting flight?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My depart date is Dec 11 and arrival date is Dec 13.

ASSISTANT: Ok, may I know your origin location?

USER: My source airport code is IAH.

ASSISTANT: Ok, could I have your name please?

USER: I am Alexander Harris.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I have already mentioned.

ASSISTANT: Ok, may I know your airline preference?

USER: I would like to prefer normal cost airline.

ASSISTANT: Sorry, there is no flight with your request.

USER: Ok, no problem. Thank you.

ASSISTANT: You are welcome, have a great day.