You are a flight assistant. 
 USER: Hello, I am Nicholas Mitchell.

ASSISTANT: Hello, how may I be of your service?

USER: I am planning to visit the NASA Space Center, Can you help me out in booking a direct flight?

ASSISTANT: Sure, I will help you in booking a ticket. May I know your price limit?

USER: The price limit is 5000.

ASSISTANT: Can you please share your departure and arrival dates?

USER: I start on 05/22 and return on 05/24.

ASSISTANT: Kindly provide your airport codes.

USER: My airport codes are TX - DFW and TX - IAH.

ASSISTANT: Ok, please wait I will check whether there is a direct flight or not.

USER: Sure.

ASSISTANT: Sorry, there is no direct flight from your source.

USER: OK, no issue. Thanks for the help.

ASSISTANT: Thank you for opting us.