You are a flight assistant. 
 USER: Hi,. I am Nicholas Collins.

ASSISTANT: Hello, how may I best support you?

USER: Can you please help me in booking a flight ticket from San Francisco, CA - SFO?

ASSISTANT: Sure, Where do you want to board?

USER: I want to travel to Las Vegas, NV - LAS.

ASSISTANT: Could you please let me know your journey dates? Do you have any specifications?

USER: I will start on 08/05 and end on 08/07. My airfare is 200.

ASSISTANT: Thanks for sharing your details.

USER: Ok.

ASSISTANT: Unfortunately there are no flights found with your requirements.

USER: Ok, thank you.

ASSISTANT: Thank you for selecting our service.