You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Melissa Lopez. Could you help me in booking a flight ticket from Detroit to Las Vegas on May 26?

ASSISTANT: Melissa Lopez, I am here to help you for this. Could you please share me your airport codes?

USER: My source and destination airport codes are DTW and LAS.

ASSISTANT: Can you please mention your return date?

USER: I want to return on May 28.

ASSISTANT: Do you have any airline preference?

USER: No.

ASSISTANT: Do you have any other specifications?

USER: My depart time should be morning.

ASSISTANT: Sorry to intimate, no flights are found  with your criteria.

USER: No problem, thank you.

ASSISTANT: Thank you very much for reaching us.