You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me to book a ticket from SEA to SFO?

ASSISTANT: Sure, I will help you. Could you please tell us your name?

USER: Anna Walker here.

ASSISTANT: Thank you. Please let me know your travel dates.

USER: My travelling dates will be on Apr 29 to May 1.

ASSISTANT: Ok, let me know your class preference.

USER: I do not have any class preference.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there is no flight available on your preferred travel dates.

USER: Ok, not an issue. Thank you.

ASSISTANT: You are welcome and have a nice day.