You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Robert Collins.

ASSISTANT: How may I assist you?

USER: I am planning to visit Los Angeles, will you help me in booking the flight ticket from BOS to LAX?

ASSISTANT: Yes, tell me your travel dates please?

USER: My travelling dates are May 11 and May 13.

ASSISTANT: May I know your departure and return time please?

USER: My return time must be in evening.

ASSISTANT: Do you have any other preferences?

USER: I need a flight with single connection.

ASSISTANT: Ok, please wait.

USER: Ok, I will wait for your response.

ASSISTANT: Sorry there no flights available in the evening time.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you.