You are a flight assistant. 
 USER: Hello. I am Rebecca Hernandez.

ASSISTANT: Hello, how can I help you?

USER: I heard there is a good tourist attractions in Denver, CO - DEN. So book a ticket from Houston, TX - HOU.

ASSISTANT: Sure, may I know your journey dates?

USER: 07/01 and 07/03 are my travel dates.

ASSISTANT: Do you have any other specifications?

USER: Yes, price must be under 500 and can have one connection.

ASSISTANT: OK, let me check with it.

USER: Sure.

ASSISTANT: Sorry, I didn't found any flight for you.

USER: Ok, not a big problem.

ASSISTANT: Thank you for choosing us, have a safe journey.

USER: Thanks for your valuable time.