Game of Eliminate

Little Ruins is a studious boy, but in rest time, he will play some little game.

Today he found a game of eliminate: there is $N \times M$ tiles which only contains '#' and '*', you have two patterns to eliminate tiles:

:.

and

.:

Each step you can use a pattern and eliminate tiles on the bottom two lines. After each step,the tiles above eliminated tiles will fall down.

Your goal is to eliminate all '*' tiles, please calculate the minimum steps.

First line contains an integer $T$, which indicates the number of test cases.

Every test case begins with two integers $N$ and $M$, which indicates the size of tiles.

In the following N lines, every line contains $M$ characters means the type of tiles.

Limits
$1 \leq T \leq 50$.
$1 \leq N \leq 2000$
$2 \leq M \leq 2000$.
For 80% of the use cases, $1 \leq N, M \leq 100$ holds.

For every test case, you should output 'Case #x: y', where x indicates the case number and counts from 1 and y is the result.

1
3 2
#*
*#
##

Case #1: 2

2016年中国大学生程序设计竞赛（杭州）