B"There is a grid with n rows and m columns. Some cells are colored black, and the rest of the cells are colored white. In one operation, you can select some black cell and do exactly one of the following: You are given two integers r and c . Find the minimum number of operations required to make the cell in row r and column c black, or determine that it is impossible. The input consists of multiple test cases. The first line contains an integer t ( 1 <= q t <= q 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 <= q n, m <= q 50 ; 1 <= q r <= q n ; 1 <= q c <= q 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. 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. 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"...