You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Stephanie Martinez here.

ASSISTANT: How can I assist you today?

USER: Can you book a direct flight to Philadelphia?

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

USER: The trip dates are from Apr 08 to Apr 10.

ASSISTANT: Do you have any preferences about class?

USER: No.

ASSISTANT: Please provide your airport codes.

USER: The airport codes are from IAD to PHL.

ASSISTANT: Please mention your name.

USER: I am Stephanie Martinez.

ASSISTANT: There are no flights found under your preferable details.

USER: Not a problem. Thank you.

ASSISTANT: Welcome, have a great day.