You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Robert Davis here.

ASSISTANT: Ok.

USER: I have planned a programme in Detroit on 05/03, So can you please book a flight ticket?

ASSISTANT: Ok, please provide your source and destination airport codes.

USER: Airport codes of my source and destinations are SFO and DTW.

ASSISTANT: Will you provide your travelling dates?

USER: Sure, my dates of travelling are 05/01 and 05/03.

ASSISTANT: Sorry to say that Robert, unfortunately there is no flights found under your required details.

USER: Oh!. It's ok, no problem. Thank you for your help.

ASSISTANT: Thanks for reaching us.Have a nice day.