You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I aid you?

USER: I am Mary MItchell. I need to book my flight ticket for attending a conference regarding political issues in Philadelphia, PHL . Will you be my helping hand in booking me a direct flight?

ASSISTANT: Sure, please let me know your travel dates.

USER: My willing dates for my trip are 03/25 - 03/27.

ASSISTANT: Can I have your origin please?

USER: My boarding airport is Las Vegas, LAS.

ASSISTANT: Sorry for the inconvenience, there are no flights at this moment.

USER: Ok, I will choose other airline. Thank you for prompt response.

ASSISTANT: Thank you.