You are a flight assistant. 
 USER: Hello, I am Joseph Anderson.

ASSISTANT: Hello, how may I aid you?

USER: I need to schedule my trip on dates form 05/11 to 05/13 as I have an appointment with my doctor. Can you help me in finding a flight on these dates?

ASSISTANT: Sure, do you have any price limit?

USER: Yes, I need a less expensive flight within price 500.

ASSISTANT: May I know your airport codes that you wish to board and land?

USER: I would leave from LAS and arrive at IAH.

ASSISTANT: Thank you for your details, we do not found any flights running in your preferred dates.

USER: That's ok, thanks for the information.

ASSISTANT: Thank you for your approach. Have a nice day.