HERDING  Herding
Oh no! A number of stray cats have been let loose in the city, and as the City Cat Catcher, you have been assigned the vital task of retrieving all of the cats. This is an ideal opportunity to test your latest invention, a cat trap which is guaranteed to retrieve every cat which walks into a squareshaped subsection of the city.
Fortunately, you have the assistance of one of the world's foremost cat psychologists, who has the amazing ability of predicting, given a square subsection of the city, exactly which of the four cardinal directions (north, east, south or west) the cat will head. While this information is handy, you still don't know where all the cats currently are.
In order to prove the costeffectiveness of your method to the City it would, of course, be important to minimize the number of traps used.
Input
The input will begin with a line consisting of two numbers n and m, separated by a space (1 ≤ n, m ≤ 1000). The city will be an n x m grid of square subsections. The next n lines will each consist of a string of length m, consisting of the letters 'N', 'E', 'S', or 'W', representing north, east, south and west, respectively. (The first character of the first line will be the northwesternmost point.) The direction in the square is the direction which cats will head if they are in that square. The cat psychologist assures you that cats have no interest in leaving the city.
Output
Output the minimum number of traps needed.
Example
Input: 3 4 SWWW SEWN EEEN Output: 2
hide comments
Nic Roets:
20120311 22:32:20
Be aware of extra blanks after 'm'.


Shaurya Gupta:
20130624 11:32:39
Why it is characterised as a BFS(Breadth First Search) problem. It does not needs BFS to be solved!! 

Mahesh Chandra Sharma:
20110519 14:28:03
REP(i, n) if (s[i][0]=='N'  s[i][m1]=='S') assert(1);


LeppyR64:
20110518 22:05:21
@Mahesh  the cats don't wantto leave. The input fits the condition. If ou still question, post your code to the forum. Last edit: 20110518 22:06:19 

Mahesh Chandra Sharma:
20110516 21:59:21
problem says: The cat psychologist assures you that cats have no interest in leaving the city.


sudipto das:
20110320 14:50:22
what is the output for:


:D:
20101014 10:50:33
Please go to the forum>ProblemSet Archive and start a subject there with your code included. We can't just GUESS the problem. 

Gaurav Munjal:
20101014 07:02:14
I am getting Runtime error NZEC in java. cana anyone help... 
Added by:  JaceTheMindSculptor 
Date:  20090407 
Time limit:  0.902s1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: C99 ERL JSRHINO 
Resource:  Canadian Computing Competition 2008 Stage 2 Day 2 Problem D 