You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Virginia Allen.

ASSISTANT: Virginia Allen. How can I help you?

USER: I would like to meet my sister at Las Vegas, please help me in booking a ticket from DCA to LAS.

ASSISTANT: May I know your travel dates please?

USER: My planned travel dates are on Mar 16 and Mar 18.

ASSISTANT: Do you have any airline preferences?

USER: Any airline is comfortable for me.

ASSISTANT: Do you have any class preferences?

USER: No, I do not have class preference.

ASSISTANT: Is there any time concern ?

USER: I would like to return in the evening.

ASSISTANT: May I know the connection limit?

USER: I do not have any connection preference.

ASSISTANT: Are there any other preferences?

USER: No.

ASSISTANT: Give me a moment please.

USER: Sure, take your time.

ASSISTANT: I regret to inform that there are no flights on your route with your requirements.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for the approach.