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.
Input
The first line contains a single string $S$ ($|S|\leq 80$) consisting of lowercase English letters.
Output
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 $0$.
Note
For the first sample, all of the non-empty subsequences of buaa are listed below:
bua(occurred twice,buaaandbuaa)buba(occurred twice,buaaandbuaa)ua(occurred twice,buaaandbuaa)aabua(occurred twice,buaaandbuaa)baauaabuaa
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 $6$.
样例
buaa
2
codeforcesround
6
oooooooooooaaaaeaaiaujooooooooooooo
24
zero
0
题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。