B"There is a rectangular maze of size n x m . Denote (r,c) as the cell on the r -th row from the top and the c -th column from the left. Two cells are adjacent if they share an edge. A path is a sequence of adjacent empty cells. Each cell is initially empty. Li Hua can choose some cells (except (x_1, y_1) and (x_2, y_2) ) and place an obstacle in each of them. He wants to know the minimum number of obstacles needed to be placed so that there isn't a path from (x_1, y_1) to (x_2, y_2) . Suppose you were Li Hua, please solve this problem. The first line contains the single integer t ( 1 <= t <= 500 ) -- the number of test cases. The first line of each test case contains two integers n,m ( 4 <= n,m <= 10^9 ) -- the size of the maze. The second line of each test case contains four integers x_1,y_1,x_2,y_2 ( 1 <= x_1,x_2 <= n, 1 <= y_1,y_2 <= m ) -- the coordinates of the start and the end. It is guaranteed that |x_1-x_2|+|y_1-y_2| ge 2 . For each test case print the minimum number of obstacles you need to put on the field so that there is no path from (x_1, y_1) to (x_2, y_2) . In test case 1, you can put obstacles on (1,3), (2,3), (3,2), (4,2) . Then the path from (2,2) to (3,3) will not exist. "...