You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Betty Garcia. I want to book a flight ticket to visit NASA Space Center with my students at HOU. Can you help me with booking under a fare of 500?

ASSISTANT: Ok, may I know your source code?

USER: My source airport code is SEA.

ASSISTANT: Fine, please mention your travel dates too.

USER: My travel dates are Feb 22 and Feb 24.

ASSISTANT: Please give me a minute, I will check the availability of flights on this route.

USER: Sure.

ASSISTANT: Sorry, there is no flight running on your route.

USER: Ok, not a problem. Thank you for your help.

ASSISTANT: Welcome, have a nice day.