You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Which service you are expecting from our agency?

USER: I am planning to book a flight ticket to SEA from BOS, can you please help me out?

ASSISTANT: Sure, I am here to help you with the ticket booking. May I know your travel dates please?

USER: Sure, my planned travelling dates are Apr 15 and 17.

ASSISTANT: Ok, please tell me your airlines preference.

USER: I prefer normal-cost airline.

ASSISTANT: OK, do you need any other requirements?

USER: Yes, I am looking for an economy class.

ASSISTANT: May I know your good name please?

USER: Sure, my name is Frank Lopez.

ASSISTANT: Sorry to tell you, there is no flight in this route with the requirements you needed.

USER: It's ok, thank you for the information.

ASSISTANT: Most welcome. Have a nice day.