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
prasoonbatham:
20161002 19:33:45
good problem! 

sushantoberoi3:
20161002 17:32:56
no dfs bfs simple recursion!! :> accepted with character array and dont use spojtoolkit for this question... 

siddharth_0196:
20160731 16:25:55
Character array gave me RE! Changed it to string and AC!


khanhpqbk:
20160722 10:57:41
got accepted in ... many goes :'( 

thaihoc06:
20160722 08:18:47
Simple DFS. AC in one go :) 

Deepak :
20160628 19:54:35
dsu..AC in one go. 

Ayon Das:
20160616 14:06:15
100th on SPOJ :D 

macbox:
20160606 19:37:05
Awesome Problem using Disjoint Set 

anirudhmenon89:
20160416 19:45:49
Flood fill algorithm works well for this problem 

xamitksx:
20160122 10:09:24
Simple problem of path count(dfs). Keeptrack of merging paths.. 
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 