
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
There are 6 contestants participating in a school singing competition. Student A guesses that contestant number 4 or 5 will win first place; Student B guesses that contestant number 3 cannot win first place; Student C guesses that one of the contestants number 1, 2, or 6 will win first place; Student D guesses that contestants number 4, 5, or 6 cannot win first place.

After the competition, it was found that there were no tied rankings, and among students A, B, C, and D, only one person guessed correctly. The contestant number of the winner is ______.

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