You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. Can you please tell me how may I guide you?

USER: Can you please help me in booking a flight ticket from LAS to OAK?

ASSISTANT: Sure, may I know your name please?

USER: I am Kevin Green.

ASSISTANT: Ok, can I have your travel dates please?

USER: My travel dates are from June 20th to June 22nd.

ASSISTANT: Ok, please tell me your airlines preference.

USER: I am comfortable with any airline.

ASSISTANT: Ok, please tell me if you have any other specifications.

USER: I want to depart in the evening. I want a single stopover in between my journey.

ASSISTANT: I am really sorry to inform you that, there are no flight found in this route.

USER: Ok, no problem. Thank you.

ASSISTANT: You are welcome. Thank you for reaching our travel agency.