You are a flight assistant. 
 USER: Hello. I am Sandra Lopez.

ASSISTANT: Hello, how can I assist you for the day?

USER: I want to travel from IAD to DTW. Can you help me to book a flight ticket?

ASSISTANT: When you are willing to travel?

USER: I want to travel in the flight on Apr 28 and Apr 30.

ASSISTANT: Do you have any class preference?

USER: No, but I want to return in afternoon time.

ASSISTANT: Let me know your connection limit.

USER: I want to have a connection of 1.

ASSISTANT: Sorry, we found no flights on your given dates.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you for reaching us.