B. Aerodynamic

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Guy-Manuel and Thomas are going to build a polygon spaceship.

You’re given a strictly convex (i. e. no three points are collinear) polygon P

which is defined by coordinates of its vertices. Define P(x,y) as a polygon obtained by translating P by vector (x,y)−→−−

. The picture below depicts an example of the translation:

Define T

as a set of points which is the union of all P(x,y) such that the origin (0,0) lies in P(x,y) (both strictly inside and on the boundary). There is also an equivalent definition: a point (x,y) lies in T only if there are two points A,B in P such that AB−→−=(x,y)−→−−. One can prove T is a polygon too. For example, if P is a regular triangle then T is a regular hexagon. At the picture below P is drawn in black and some P(x,y)

which contain the origin are drawn in colored:

The spaceship has the best aerodynamic performance if P

and T are similar. Your task is to check whether the polygons P and T

are similar.

Input

The first line of input will contain a single integer n

(3≤n≤105

) — the number of points.

The i

-th of the next n lines contains two integers xi,yi (|xi|,|yi|≤109), denoting the coordinates of the i

-th vertex.

It is guaranteed that these points are listed in counterclockwise order and these points form a strictly convex polygon.

Output

Output “YES” in a separate line, if P

and T

are similar. Otherwise, output “NO” in a separate line. You can print each letter in any case (upper or lower).

Examples

Input

Copy

4

1 0

4 1

3 4

0 3

Output

Copy

YES

Input

Copy

3

100 86

50 0

150 0

Output

Copy

nO

Input

Copy

8

0 0

1 0

2 1

3 3

4 6

3 6

2 5

1 3

Output

Copy

YES

Note

The following image shows the first sample: both P

and T

are squares. The second sample was shown in the statements.

点是odd数肯定不行

然后就是对边平行且相等就OK了

然后我不懂为何对角线的坐标相加相等就OK了

最后修改日期:2020年2月10日

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