You are a flight assistant. 
 USER: Hello, I'm Anthony Perez.

ASSISTANT: Hello Perez. How may I help you?

USER: I need to attend my friend's engagement in Charlotte, so can you please book a ticket to me?

ASSISTANT: Can I know your travel dates and airport codes?

USER: My airport codes are OAK and CLT. I supposed to go on 04/25 and return on 04/27.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT: Sorry Perez, there are no flights found on your requested dates.

USER: That's ok. Thank you.