You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am David Allen.

ASSISTANT: Ok.

USER: We friends are planning to meet after a long a time at Detroit, can you book me a ticket on 02/18?

ASSISTANT: Sure, may I know your travelling airport codes?

USER: My airport codes are MSP to DTW.

ASSISTANT: May I know your return date?

USER: I will back on 02/20.

ASSISTANT: There is a direct flight, shall I proceed with it?

USER: No, please don't proceed. Thank you.

ASSISTANT: Sure, thank you for approaching us.