You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Anna Phillips.

ASSISTANT: How can I help you?

USER: Can you please book a flight ticket from MSP to DEN?

ASSISTANT: Let me know your travelling dates.

USER: Sure, I need to travel on dates of May 19 and May 21.

ASSISTANT: Do you have any preference?

USER: I would like to depart in the evening time.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you.