#P1147B. Chladni Figure
Chladni Figure
No submission language available for this problem.
Description
Inaka has a disc, the circumference of which is $n$ units. The circumference is equally divided by $n$ points numbered clockwise from $1$ to $n$, such that points $i$ and $i + 1$ ($1 \leq i < n$) are adjacent, and so are points $n$ and $1$.
There are $m$ straight segments on the disc, the endpoints of which are all among the aforementioned $n$ points.
Inaka wants to know if her image is rotationally symmetrical, i.e. if there is an integer $k$ ($1 \leq k < n$), such that if all segments are rotated clockwise around the center of the circle by $k$ units, the new image will be the same as the original one.
The first line contains two space-separated integers $n$ and $m$ ($2 \leq n \leq 100\,000$, $1 \leq m \leq 200\,000$) — the number of points and the number of segments, respectively.
The $i$-th of the following $m$ lines contains two space-separated integers $a_i$ and $b_i$ ($1 \leq a_i, b_i \leq n$, $a_i \neq b_i$) that describe a segment connecting points $a_i$ and $b_i$.
It is guaranteed that no segments coincide.
Output one line — "Yes" if the image is rotationally symmetrical, and "No" otherwise (both excluding quotation marks).
You can output each letter in any case (upper or lower).
Input
The first line contains two space-separated integers $n$ and $m$ ($2 \leq n \leq 100\,000$, $1 \leq m \leq 200\,000$) — the number of points and the number of segments, respectively.
The $i$-th of the following $m$ lines contains two space-separated integers $a_i$ and $b_i$ ($1 \leq a_i, b_i \leq n$, $a_i \neq b_i$) that describe a segment connecting points $a_i$ and $b_i$.
It is guaranteed that no segments coincide.
Output
Output one line — "Yes" if the image is rotationally symmetrical, and "No" otherwise (both excluding quotation marks).
You can output each letter in any case (upper or lower).
Samples
12 6
1 3
3 7
5 7
7 11
9 11
11 3
Yes
9 6
4 5
5 6
7 8
8 9
1 2
2 3
Yes
10 3
1 2
3 2
7 2
No
10 2
1 6
2 7
Yes
Note
The first two examples are illustrated below. Both images become the same as their respective original ones after a clockwise rotation of $120$ degrees around the center.