Problem Description

Lana likes drawing snowflakes. A snowflake of size $x$ is defined as follows.

• The center of the snowflake is a $\texttt{'+'}$.
• There are $x$ $\texttt{'|'}$ characters above and $x$ $\texttt{'|'}$ characters below the $\texttt{'+'}$.
• There are $x$ $\texttt{'-'}$ characters to the left and $x$ $\texttt{'-'}$ characters to the right of the $\texttt{'+'}$.
• There are $x$ $\texttt{'\textbackslash'}$ characters to the upper-left and $x$ $\texttt{'\textbackslash'}$ characters to the lower-right of the $\texttt{'+'}$.
• There are $x$ $\texttt{'/'}$ characters to the lower-left and $x$ $\texttt{'/'}$ characters to the upper-right of the $\texttt{'+'}$.

Snowflakes may overlap. Below are some examples of snowflakes.

The three pictures contain, respectively: one snowflake of size $1$; two overlapping snowflakes of sizes $2$ and $1$; and one snowflake of size $1$ (because a size $2$ snowflake is incomplete).

Given an $n \times m$ character matrix, find the size of the largest snowflake in it.

Input Format

The first line contains two integers $n, m$.

The next $n$ lines each contain a string of length $m$, describing an $n \times m$ matrix. It is guaranteed to contain only $\texttt{'+'}, \texttt{'-'}, \texttt{'|'}, \texttt{'/'}, \texttt{'\textbackslash'}, \texttt{'.'}$.

Output Format

Output one integer: the size of the largest snowflake. If there is none, output $0$.

5 6
\.\|/.
---+--
/./|\.
./.|.\
/..|..

1

7 7
\.|./..
.\|/...
--+--..
./|\...
/.|.\|/
....-+-
..../|\

2

7 7
\|/|\|/
-+-|-+-
/|\|/|\
---+---
\|/|\|/
-+-|-+-
/|\|/|\

1

Hint

Constraints

For all testdata, $1 \le n, m \le 50$.

Translated by ChatGPT 5