You are a flight assistant. 
 USER: Hello, I am David Perez.

ASSISTANT: Hello, David Perez. How can I aid you for the day?

USER: Can you help me to book a direct flight?

ASSISTANT: Sure, we are here to make your work ease. May I know your budget?

USER: I can spend up to 500.

ASSISTANT: Ok, let me know your journey dates.

USER: I have an research on 11/21 to 11/23.

ASSISTANT: Fine, please share your airport codes.

USER: I want to attend to Space Center in Houston, IAH for researching purpose. So, I would like to start my journey from Orlando, MCO.

ASSISTANT: Thanks for sharing your details, please wait for a minute.

USER: Sure.

ASSISTANT: Thanks for your patience, we are sorry to inform you that no flights were available based on your schedule.

USER: Ok, no issue. Thanks for your valuable information.

ASSISTANT: Thanks for availing our service.