Good Bye 2016
B
New Year and North Pole
Codeforces
1300
原题
← AC →
翻译中…

In this problem we assume the Earth to be a completely round ball and its surface a perfect sphere. The length of the equator and any meridian is considered to be exactly $40 000$ kilometers. Thus, travelling from North Pole to South Pole or vice versa takes exactly $20 000$ kilometers.

翻译中…

Limak, a polar bear, lives on the North Pole. Close to the New Year, he helps somebody with delivering packages all around the world. Instead of coordinates of places to visit, Limak got a description how he should move, assuming that he starts from the North Pole. The description consists of $*n*$ parts. In the $*i*$-th part of his journey, Limak should move $*t*_{*i*}$ kilometers in the direction represented by a string $*dir*_{*i*}$ that is one of: "North", "South", "West", "East".

翻译中…

Limak isn’t sure whether the description is valid. You must help him to check the following conditions:

翻译中…
  • If at any moment of time (before any of the instructions or while performing one of them) Limak is on the North Pole, he can move only to the South.
  • If at any moment of time (before any of the instructions or while performing one of them) Limak is on the South Pole, he can move only to the North.
  • The journey must end on the North Pole.
翻译中…

Check if the above conditions are satisfied and print "YES" or "NO" on a single line.

翻译中…

Input

翻译中…

The first line of the input contains a single integer $*n*$ ($1 ≤ *n* ≤ 50$).

翻译中…

The $*i*$-th of next $*n*$ lines contains an integer $*t*_{*i*}$ and a string $*dir*_{*i*}$ ($1 ≤ *t*_{*i*} ≤ 10^{6}$, image) — the length and the direction of the $*i*$-th part of the journey, according to the description Limak got.

翻译中…

Output

翻译中…

Print "YES" if the description satisfies the three conditions, otherwise print "NO", both without the quotes.

翻译中…

Note

翻译中…

Drawings below show how Limak's journey would look like in first two samples. In the second sample the answer is "NO" because he doesn't end on the North Pole.

翻译中…

image

翻译中…

样例

Input #1
5
7500 South
10000 East
3500 North
4444 West
4000 North
Output #1
YES
InputCopy OutputCopy
Input #2
2
15000 South
4000 East
Output #2
NO
InputCopy OutputCopy
Input #3
5
20000 South
1000 North
1000000 West
9000 North
10000 North
Output #3
YES
InputCopy OutputCopy
Input #4
3
20000 South
10 East
20000 North
Output #4
NO
InputCopy OutputCopy
Input #5
2
1000 North
1000 South
Output #5
NO
InputCopy OutputCopy
Input #6
4
50 South
50 North
15000 South
15000 North
Output #6
YES
InputCopy OutputCopy
题目信息
题号
750B
所属比赛
时间限制
2 s
内存限制
256 MB
标签
计算几何
模拟

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。