| UTPC April Fools Contest 2026 |
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| Finished |
Castor is taking a number theory course. Help him answer a question from his class:
Partition the first $$$n$$$ positive integers into $$$k$$$ sets such that numbers in each set are pairwise coprime, and print out your construction. Also, $$$k$$$ must be minimal.
The first line contains $$$n$$$ $$$(4\le n\le 3\cdot 10^5)$$$
Print out $$$k$$$ lines, each containing $$$m_i$$$ followed by $$$m_i$$$ integers $$$a_{i,1},a_{i,2},\cdots,a_{i,m_i}$$$ — representing the $$$i$$$th set of the partition. Do not print out $$$k$$$ itself.
Also, if you print out extra things at the end, the checker will ignore them. :)
10
[sorry, we don't have the answer to the sample]
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