
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Mr. Zhao, Mr. Qian, and Mr. Sun all know that there are 16 playing cards in the drawer of the table: Hearts A, Q, 4; Spades J, 8, 4, 2, 7, 3; Clubs K, Q, 5, 4, 6; Diamonds A, 5. Professor Li picks one of these 16 cards and tells Mr. Qian the rank of the card and tells Mr. Sun the suit of the card. Then, Professor Li asks Mr. Qian and Mr. Sun: Can you deduce what card this is based on the rank or suit you know? Mr. Zhao hears the following conversation:
Mr. Qian: I don't know what card this is.
Mr. Sun: I know you don't know what card this is.
Mr. Qian: Now I know what card it is.
Mr. Sun: I also know now.
After hearing this conversation, Mr. Zhao thought for a while and then correctly deduced what card it was.
What is the card?

Present the answer in LaTex format: \boxed{Your answer}
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