You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Dennis Davis.

ASSISTANT: How may I help you? Nice to meet you Dennis.

USER: Please help in booking my flight ticket from MSP to SFO?

ASSISTANT: Sure, tell me your travel dates please?

USER: My travelling dates are Apr 19 and APR 21.

ASSISTANT: Please wait. Thanks for waiting. But I am sorry to say that there are no flights available.

USER: Ok. Thank you for checking.

ASSISTANT: Thank you.