You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I need a direct flight to Denver to be with my friend as he met with an accident. Please help me with booking a ticket.

ASSISTANT: Sure, Can you share me your trip dates for booking purpose?

USER: Sure, I want to fly on 02/11 and will return on 02/13.

ASSISTANT: May I know your name?

USER: I am Charles Martin.

ASSISTANT: Let me know your airport codes?

USER: Its from CA-OAK to CO-DEN.

ASSISTANT: Ok, wait for some time.

USER: Sure.

ASSISTANT: Unfortunately there is no flights found on your details.

USER: It's Ok, thanks for the information.

ASSISTANT: Thanks for choosing us.