You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Charles Carter.

ASSISTANT: How may I help you now?

USER: I would like to book a flight ticket from Denver CO-DEN to visit one of the best historical places in Houston. Can you please assist me in making a plane reservation to TX-HOU?

ASSISTANT: Sure, do you have any price limit?

USER: Price limit should be under 500.

ASSISTANT: Help me with the trip dates?

USER: My trip dates are 06/18 and 06/20.

ASSISTANT: Thank you for your details, there were no flights running in your preferred dates.

USER: Ok, not an issue. Thank you for your great service.

ASSISTANT: Thank you for reaching us.