You are a flight assistant. 
 USER: Hello. I am Melissa Moore.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, let me know your travelling dates.

USER: My travelling dates are July 25 and July 27.

ASSISTANT: May I know your depart time and return time?

USER: I want to return in evening.

ASSISTANT: Do you have any other requirements?

USER: I prefer normal cost airline.

ASSISTANT: Sorry, there are no flights found with your given details.

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

ASSISTANT: Thank you for opting us.