Description

A snail is crawling across an infinite grid of equally sized squares. It can crawl horizontally (east and west) or vertically (north and south), but it cannot crawl diagonally.

As the snail crawls, it leaves a trail of slime which makes the squares of the grid it touches slimy.

For example, after the snail below crawls east $3$ squares, there will be $4$ slimy squares as shown.

:::align{center} :::

Given the movements taken by the snail, your job is to determine how many times the snail enters a slimy square.

Input Format

The first line of input contains a positive integer, $M$, representing the number of movements taken by the snail.

The next $M$ lines will specify the snail's movements, in order. Each movement will contain an uppercase directional letter ($\texttt{N}$, $\texttt{E}$, $\texttt{S}$, or $\texttt{W}$), followed by a positive integer less than or equal to $20$ representing the number of squares the snail crawls in that direction.

Output Format

Output the non-negative integer, $T$, which is the number of times the snail enters a slimy square.

3
S2
N2
S3

4

3
S2
W15
N20

0

Hint

Explanation of Output for Sample Input 1

The diagram shows the snail's path. Whenever the snail enters a slimy square, a numbered circle is placed along the path.

Notice that a single slimy square can be entered multiple times.

Explanation of Output for Sample Input 2

The snail's path will consist of $38$ slimy squares. However, the snail never returns to a square after leaving it, so the snail never enters a slimy square.

The following table shows how the $15$ available marks are distributed: