You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I am Richard Lopez want to visit DEN, can you book a ticket from PHL?

ASSISTANT: Sure, I will help you with that. Can you please share your journey dates?

USER: Sure, my travelling dates will be 10/14 and 10/16.

ASSISTANT: I am sorry to say that there is no flight found.

USER: That's ok, thank you.

ASSISTANT: Thank you for contacting us.