You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you?

USER: I am Melissa Jackson. I would like to book a ticket to San Francisco, can you please help me out?

ASSISTANT: Yes, can you please let me know your travelling dates?

USER: I am travelling on these dates 01/23 and 01/25.

ASSISTANT: Can you please provide your location codes?

USER: I am flying from OAK to SFO.

ASSISTANT: Thank you for your information.

USER: Ok.

ASSISTANT: I am unable to find a flight on the dates which your prefer in your journey.

USER: Ok no problem, thank you for your services.

ASSISTANT: It's my pleasure.