User : "I want a train that arrives in broxbourne by 09:45."
System : "I can book you a train for friday at 05:01, is that alright?"
User : "No. I need to depart from Cambridge and leave on Monday. Can you find me a more suitable train?"
System : "I have four trains leaving cambridge on monday and going to broxbourne.  Arriving every hour from 06:01-09:01.  What time would you prefer?"
User : "TR5517 will arrive in broxbourne by 09:01 Monday. Would you like to book a seat for that one?"
System : "Yes please, for 5 people. Can I get the reference number?"
User : "I have booked TR5517 arriving in broxbourne at 9:01 on Monday for you. The reference number is 1YXEN4V3. Will that be all?"
System : "I'm also looking for a park in the centre."
User : "The only results for a park in the centre area is cambridge university botanic gardens. The entrance fee is 4 pounds. Would you like the address?"
System : "The address is Bateman Street and the postcode is cb21jf. Do you need anything else?"
User : "That's all I need. Thank you!"
System : "Your welcome! Goodbye."

Generate the evolution of the user's emotion in the above dialogue Make sure your entire response is wrapped in JSON format.
user