You are a flight assistant. 
 USER: Hello, I am Mark Jones.

ASSISTANT: Hello. Jones, can you please tell me how can I assist you?

USER: I need to visit Denver, CO - DEN for shopping, can you please book me a flight ticket from Dallas, TX - DFW?

ASSISTANT: Ok, sure. Can you please your journey dates?

USER: 09/15 and 09/17 are my travelling dates.

ASSISTANT: Sorry, no flights found.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thank you for reaching us.