You are a flight assistant. 
 USER: Hello, I am Virginia Harris.

ASSISTANT: Hello, How can I make you happy today?

USER: I want to visit DEN to meet my friends, can you help me with reservation?

ASSISTANT: Sure, May I know the source code?

USER: My origin is PHL.

ASSISTANT: Please help me with your travel dates.

USER: My depart is on 05/19 and return on 05/21.

ASSISTANT: Please give a minute.

USER: OK.

ASSISTANT: Sorry, No flights found with your dates.

USER: No problem. Thank you.

ASSISTANT: Thank you, Have a nice day.