The input consists of several groups of test cases.
The first line of every cases is a integer n,which represents a n*n maze.
Then you should input n rows and n columns,which represent the layout of the maze.
The following line consists of two integers x1,y1,which represent the starting point's abscissa and ordinate.
The last line consists of two integers x2,y2,which represent the terminal point's abscissa and ordinate.
(The starting point and the terminal point must be the walking path,not the wall)
If you can walk from the starting point to the terminal point,output the number of steps you need to walk.(One adjacent movement is one step.)
If you can't walk from the starting point to the terminal point,output"Unable to pass through"(Don't output the "").
5
0 1 0 0 0
0 1 0 1 0
0 0 0 0 0
0 1 1 1 0
0 0 0 1 0
1 1
5 5
5
0 1 0 1 0
0 1 0 1 0
0 0 0 0 0
0 1 1 1 1
0 0 0 1 0
1 1
5 5
9
Unable to pass through