You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Lisa Johnson.

ASSISTANT: Lisa, how can I assist you?

USER: I am planning to travel from SFO to PHL to attend a convocation meeting, can you please help me with booking a flight ticket?

ASSISTANT: Sure, I can help you. Please provide your airport codes.

USER: My departure date is on 07/19 and the return date is on 07/21.

ASSISTANT: Let me check.

USER: Sure.

ASSISTANT: Sorry, no flight's found for you.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for reaching us.