You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Alexander Parker here.

ASSISTANT: How can I assist you?

USER: Please help me out in booking the ticket from 12/23 to 12/25.

ASSISTANT: Yes, can you tell me your nearest airport codes?

USER: My airport codes will be HOU to IAD.

ASSISTANT: Give me a moment.

USER: Ok, take your time.

ASSISTANT: Sorry to inform you that there are no flights found on your requested dates.

USER: That's ok, not a problem.

ASSISTANT: Thank you for contacting us.

USER: Thank you for informing.