19422번 - Almost Bobo Number 다국어

A positive integer is called a bobo number if its decimal representation can be obtained by concatenating two copies of the same integer. For example, $12341234$ and $3232$ are bobo numbers, while $1234321$ and $1322$ are not.

A positive integer is called an almost bobo number if, after merging all the consecutive equal digits, the resulting number is a bobo number. For example, $\underbrace{111}\underbrace{222}\underbrace{3}\underbrace{11}\underbrace{22}\underbrace{33}$ becomes $123123$ after merging all the consecutive equal digits, and thus is an almost bobo number.

Bobo has a very large number $n$, and he would like to know the largest almomst bobo number less than $n$.

The input contains zero or more test cases, and is terminated by end-of-file. For each test case:

The first line contains an integer $n$ without leading zeros ($1 \leq n \leq 10^{5\,000\,000}$).

It is guaranteed that the total length of the decimal representations of all $n$ in the input does not exceed $5\,000\,000$.

For each test case, output an integer without leading zeros denoting the largest almomst bobo number strictly less than $n$. If there is no such integer, output $-1$ instead.