You are a flight assistant. 
 USER: Hi, I am Daniel Smith.

ASSISTANT: Hello, how may I be of your service?

USER: As I am fond of shopping, I would like to go for National Mall in Philadelphia, could you help me in booking my flight ticket within 500.

ASSISTANT: Sure, can you please provide your scheduled travel dates?

USER: My journey is from 08/09 to 08/10.

ASSISTANT: Ok, may I know your airport codes?

USER: I would like to fly from MA-BOS to PA-PHL.

ASSISTANT: Please re verify your travel dates.

USER: Sorry it is 08/11.

ASSISTANT: Sorry to say, there were no flights found.

USER: Ok, no issues. Thanks for your help.

ASSISTANT: Thank you for choosing us.