You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Jack Lee.

ASSISTANT: How may I aid you today?

USER: I want to book a flight ticket on 12/22 and 12/24. Can you help me?

ASSISTANT: Sure, may I know your airport codes?

USER: SFO and EWR are my airport codes.

ASSISTANT: We do not found any flights running in your desired routes.

USER: No issue. Thank you.

ASSISTANT: Thank you for reaching us.