# #4512. [Usaco2016 Jan] Build Gates

#### 题目描述

Farmer John decides to build a new fence around parts of his farm, but he keeps getting distracted a
nd ends up building the fence into a much stranger shape than he intended!Specifically, FJ starts at
position (0,0)and takes N steps, each moving one unit of distance north, south, east, or west. Each
step he takes, he lays a unit of fence behind him. For example, if his first step is to the north,
he adds a segment of fence from (0,0) to (0,1). FJ might re-visit points multiple times and he may e
ven lay the same segment of fence multiple times. His fence might even cross over itself if his path
cuts through a run of fencing he has already built.Needless to say, FJ is rather dismayed at the re
sult after he completes the fence. In particular, he notices that it may be the case that he has now
partitioned off some areas of the farm from others, so that one can no longer walk from one region
to another without crossing a fence. FJ would like to add gates to his fences to fix this problem. A
gate can be added to any unit-length segment of fence he has built, allowing passage between the tw
o sides of this segment.Please determine the minimum number of gates FJ needs to build so that every
region of the farm is once again reachable from every other region.

,0)点，要向N移动，则FJ移动到(0,1)，并在(0,0)和(0,1)之间建一段篱笆。注意到这样建设出的篱笆可能自交，

#### 输入格式

The first line of input contains N(1≤N≤1000). The next line contains a string of length N
describing FJ's path. Each character is either N (north), E (east), S (south), or W (west).

#### 输出格式

Write out a single integer giving the minimum number of gates FJ needs to build to restore complete connectivity to all regions of his farm. Note that the answer could be zero if the farm is connected to begin with.

#### 样例输入

``````
14
NNNESWWWSSEEEE
``````

#### 样例输出

``````
2``````