You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What else can I help you today?

USER: My name is Margaret Roberts.

ASSISTANT: Nice to meet you Roberts.

USER: I am planning to visit OAk for two days and trying to book a plane ticket from SFO.

ASSISTANT: Ok fine. On which dates you want to travel?

USER: My travelling dates are from 05/16 to 05/18.

ASSISTANT: Please wait for a minute.

USER: Ok.

ASSISTANT: Sorry, we cannot find any flight with your travel dates.

USER: No problem, thank you for your service.

ASSISTANT: It's my pleasure.