You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is Sharon Martinez.

ASSISTANT: Sharon, how may I help you?

USER:  I am planning to go to round trip, can you help me to book a ticket from SFO?

ASSISTANT: Please share your trip dates.

USER: Sure, my planned dates of trip are 12/23 and 12/25.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, no flight is available.

USER: It's ok, no problem.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your information.