Given the following slots in JSON:
"slots": {
        "train-departure": null,
        "train-destination": null,
        "train-arriveby": null,
        "train-day": null,
        "train-leaveat": null
    }

Extract the slot values from the following dialogue.
---
User: "I need train reservations from norwich to cambridge"
System: "I have 133 trains matching your request. Is there a specific day and time you would like to travel?"
User: "I'd like to leave on Monday and arrive by 18:00."
System: "There are 12 trains for the day and time you request. Would you like to book it now?"
User: "Before booking, I would also like to know the travel time, price, and departure time please."
System: "There are 12 trains meeting your needs with the first leaving at 05:16 and the last one leaving at 16:16. Do you want to book one of these?"
User: "Yes, thank you."
---

Give the answer also in JSON.