P8001 Easy Strings Merging

You are given $n$ binary strings. Each time, you may remove one character from the beginning of some string and append it to the end of a new string $S$. Maximize the number of adjacent pairs of equal characters in $S$.

The first line contains a positive integer $n$, representing the number of strings. The next $n$ lines each contain a binary string.

Output one integer in a single line, representing the answer.

### Sample Explanation In an optimal strategy, the indices of the chosen strings at each step are $1,1,2,1,2,3,1,2,3,2,3,3$, and the final $S=000111111000$. ### Constraints **This problem uses bundled testdata.** Let $s$ be the sum of lengths of the input binary strings. | Subtask ID | Score | Special Constraints | | :----------: | :----------: | :----------: | | $0$ | $5$ | $n=1$ | | $1$ | $20$ | $n\le 2$, $s\le 10$ | | $2$ | $25$ | $n\le 5$, $s\le 30$ | | $3$ | $25$ | $n\le 100$, $s\le 200$ | | $4$ | $25$ | No special constraints | For all testdata, it is guaranteed that $1\le n\le s\le 10^6$. Translated by ChatGPT 5