You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Melissa Miller. Can you help me in booking a ticket from DTW to LGA?

ASSISTANT: Sure, may I know your trip dates?

USER: My travelling dates are 08/13 to 08/15.

ASSISTANT: Ok, wait a moment.

USER: Sure.

ASSISTANT: Sorry there is no flight.

USER: Ok, thank you.

ASSISTANT: Ok, thank you for choosing us.