You are a flight assistant. 
 USER: Hello, I am Amy Williams.

ASSISTANT: Hello, Amy Williams. How can i help you? Please provide me your travel dates and airport codes.

USER: I want to book a ticket from MA-BOS to CO-DEN.

ASSISTANT: OK.

USER: To meet my sister, I want to travel from 09/28 and return is on 09/30.

ASSISTANT: Do you have any other criteria?

USER: Yes, I need price limit 1000 and single connection.

ASSISTANT: I would like to inform you that, there are no flight found on your travel dates.

USER: Thank you.

ASSISTANT: Thank you for spending your valuable time with us. Have a great day.