You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hi,.

USER: My name is Edward Wilson.

ASSISTANT: How may I assist you?

USER: I want to spend my summer vacations in my sister's house, so please book a flight ticket from MN-MSP to TX-DFW. My departure day is 05/20, return day is 05/22.

ASSISTANT: OK,give me a minute,I will get back to you.

USER: Ok.

ASSISTANT: sorry to inform you,no flights found on your journey dates. Thank you for choosing us. Have a nice day.

USER: No problem, thank you.