Codeforces Round 853 (Div. 2) |
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Finished |
Serval loves Brain Power and his brain power problem.
Serval defines that a string $$$T$$$ is powerful iff $$$T$$$ can be obtained by concatenating some string $$$T'$$$ multiple times. Formally speaking, $$$T$$$ is powerful iff there exist a string $$$T'$$$ and an integer $$$k\geq 2$$$ such that $$$$$$T=\underbrace{T'+T'+\dots+T'}_{k\text{ times}}$$$$$$
For example, gogogo is powerful because it can be obtained by concatenating go three times, but power is not powerful.
Serval has a string $$$S$$$ consists of lowercase English letters. He is curious about the longest powerful subsequence of $$$S$$$, and he only needs you to find out the length of it. If all the non-empty subsequences of $$$S$$$ is not powerful, the answer is considered to be $$$0$$$.
A string $$$a$$$ is a subsequence of a string $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by the deletion of several (possibly, zero or all) characters.
The first line contains a single string $$$S$$$ ($$$|S|\leq 80$$$) consisting of lowercase English letters.
Print a single integer — the length of the longest powerful subsequence of $$$S$$$. If all the non-empty subsequences of $$$S$$$ is not powerful, print $$$0$$$.
buaa
2
codeforcesround
6
oooooooooooaaaaeaaiaujooooooooooooo
24
zero
0
For the first sample, all of the non-empty subsequences of buaa are listed below:
Since $$$\texttt{aa} = \texttt{a} + \texttt{a}$$$, aa is a powerful subsequence. It can be shown that aa is the only powerful subsequence among them. So the answer is $$$2$$$.
For the second sample, the longest powerful subsequence is codcod from codeforcesround. So the answer is $$$6$$$.
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