You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I help you?

USER: I am Gregory Mitchell. I would like to attend a film festival at Houston with my friends, so can you help me with booking a flight ticket?

ASSISTANT: Sure, may I know your source and destination airport codes?

USER: My source is Denver, DEN and destination is Houston, HOU.

ASSISTANT: Could you please provide me your planned journey dates?

USER: I am planning to start on 04/21 and intend to return on 04/23.

ASSISTANT: Do you want connecting flight?

USER: Yes, I need a connecting flight.

ASSISTANT: Sorry, there are no connecting flights found with your given dates.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for opting us.