2020-2021 ICPC, NERC, Southern and Volga Russian Regional Contest (Online Mirror, ICPC Rules) |
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Finished |
Suppose you have a sequence of $$$k$$$ integers $$$A = [a_1, a_2, \dots , a_k]$$$ where each $$$a_i \geq 2$$$. A sequence of prime integers $$$P = [p_1, p_2, \dots, p_k]$$$ is called suitable for the sequence $$$A$$$ if $$$a_1$$$ is divisible by $$$p_1$$$, $$$a_2$$$ is divisible by $$$p_2$$$ and so on.
A sequence of prime integers $$$P$$$ is called friendly if there are no unique integers in this sequence.
A sequence $$$A$$$ is called ideal, if each sequence $$$P$$$ that is suitable for $$$A$$$ is friendly as well (i. e. there is no sequence $$$P$$$ that is suitable for $$$A$$$, but not friendly). For example, the sequence $$$[2, 4, 16]$$$ is ideal, while the sequence $$$[2, 4, 6]$$$ is not ideal (there exists a sequence $$$P = [2, 2, 3]$$$ which is suitable for $$$A$$$, but not friendly).
You are given $$$n$$$ different integers $$$x_1$$$, $$$x_2$$$, ..., $$$x_n$$$. You have to choose exactly $$$k$$$ of them in such a way that they form an ideal sequence, or report that it is impossible. Note that no integer can be chosen more than once.
The first line contains two integers $$$n$$$ and $$$k$$$ ($$$1 \leq k \leq n \leq 1000$$$).
The second line contains $$$n$$$ pairwise distinct integers $$$x_1$$$, $$$x_2$$$, ..., $$$x_n$$$ ($$$2 \leq x_i \leq 10^{18}$$$).
If it is impossible to choose exactly $$$k$$$ integers from $$$x_1$$$, $$$x_2$$$, ..., $$$x_n$$$ in such a way that the chosen integers form an ideal sequence, print $$$0$$$.
Otherwise, print $$$k$$$ pairwise distinct integers — the elements of the chosen ideal sequence. If there are multiple answers, print any of them.
3 3
2 4 6
0
3 3
2 4 16
2 4 16
4 3
2 4 6 16
2 4 16
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