You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you please book a flight ticket to my father?

ASSISTANT: Sure, will you mention your travelling dates please?

USER: Ok, the dates of his journey are 10/28 and 10/30.

ASSISTANT: Please provide the airport codes.

USER: He want to depart at DEN and landing at PHL airport.

ASSISTANT: Please give me a moment.

USER: Ok.

ASSISTANT: Please provide your father name.

USER: My father name is Jack Williams.

ASSISTANT: There is no flights available on your preferable details.

USER: It's ok, thank you for searching.

ASSISTANT: Thanks for reaching us, have a great day.