You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am looking for a flight from DEN to BOS, can you please help me in booking?

ASSISTANT: Sure, please share your journey dates?

USER: I will start my journey on Aug 17 and return back on Aug 19.

ASSISTANT: Do you have any specifications?

USER: I want to return in evening.

ASSISTANT: Is there any class preference?

USER: I am fine with any class.

ASSISTANT: May I know your good name?

USER: My name is Jessica Green.

ASSISTANT: Sorry, no flights found on your given details.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.