You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I be of your help?

USER:  Can you please book a ticket in the name of Emma Hernandez, from MA - BOS, to CO - DEN?

ASSISTANT: Sure, can I have your travel dates?

USER: My travelling dates are: start on 08/09, and return on 08/11.

ASSISTANT: How much you can afford for this journey?

USER: I can afford only 200.

ASSISTANT: Sorry, there are no flights with your requirement.

USER: Ok, thanks for your kind information.

ASSISTANT: Have a good day.