Description
There is a 
grid. Each cell 
contains exactly one integer 
.
You are on 
in the beginning and want to go to 
.
You could move to an adjacent cell if the integer of it is greater than or equal to the integer of the cell which you are on. An adjacent cell is a cell which shares a common side with the cell which you are on.
Find the minimum number of cells you need to pass by to reach . There may be no such a path for you to reach .
Input
The first line contains two positive integers 
and 
– the size of the grid.
Then lines folllow. The 
-th line contains 
integers. The 
-th integer in the 
-th line 
is the integer of the cell 
.
The next line contains two integers 
and 
– the initial cell you are on.
The final line contains two integers 
and 
– the cell you want to go.
Note that and must be different(i.e 
or 
).
It's guaranteed that:
- The 1st testcase must be identical to the Sample #1 below
- For the first 6 testcases:
and 
Output
Output the minimum cells you must pass by for you to reach 
. Output -1 instead if there is no such a path.
Remember to print a newline('\n') character at the end of the line.
Note: there are two sample below. "# Sample Input 1/2/3" and "# Sample Output 1/2/3" are not the part of input and output.
They are just for marking that the following content corresponds to which sample.