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Description:

Input:

The input consists of multiple test cases. The first line contains an integer $$$t$$$ ($$$1 \leq t \leq 100$$$) — the number of test cases. The description of the test cases follows.

The first line of each test case contains four integers $$$n$$$, $$$m$$$, $$$r$$$, and $$$c$$$ ($$$1 \leq n, m \leq 50$$$; $$$1 \leq r \leq n$$$; $$$1 \leq c \leq m$$$) — the number of rows and the number of columns in the grid, and the row and column of the cell you need to turn black, respectively.

Then $$$n$$$ lines follow, each containing $$$m$$$ characters. Each of these characters is either 'B' or 'W' — a black and a white cell, respectively.

Output:

For each test case, if it is impossible to make the cell in row $$$r$$$ and column $$$c$$$ black, output $$$-1$$$.

Otherwise, output a single integer — the minimum number of operations required to make the cell in row $$$r$$$ and column $$$c$$$ black.

Sample Input:

9
3 5 1 4
WBWWW
BBBWB
WWBBB
4 3 2 1
BWW
BBW
WBB
WWB
2 3 2 2
WWW
WWW
2 2 1 1
WW
WB
5 9 5 9
WWWWWWWWW
WBWBWBBBW
WBBBWWBWW
WBWBWBBBW
WWWWWWWWW
1 1 1 1
B
1 1 1 1
W
1 2 1 1
WB
2 1 1 1
W
B

Sample Output:

1
0
-1
2
2
0
-1
1
1

Note:

The first test case is pictured below.

We can take the black cell in row $$$1$$$ and column $$$2$$$, and make all cells in its row black. Therefore, the cell in row $$$1$$$ and column $$$4$$$ will become black.

In the second test case, the cell in row $$$2$$$ and column $$$1$$$ is already black.

In the third test case, it is impossible to make the cell in row $$$2$$$ and column $$$2$$$ black.

The fourth test case is pictured below.

We can take the black cell in row $$$2$$$ and column $$$2$$$ and make its column black.

Then, we can take the black cell in row $$$1$$$ and column $$$2$$$ and make its row black.

Therefore, the cell in row $$$1$$$ and column $$$1$$$ will become black.