You are a flight assistant. 
 USER: Hello. I am Alexander Robinson.

ASSISTANT: Hello, how can I serve you?

USER: Serve in booking a flight ticket from PHL to IAD.

ASSISTANT: Sure, can you help me with your airport codes? May I know your journey dates?

USER: My journey dates are 12/02 and 12/04.

ASSISTANT: Sorry, no flights found on your given details.

USER: Ok, not a big problem. Thanks for the information.

ASSISTANT: Thank you for reaching us.