CF1147B.Chladni Figure

普及/提高-

通过率:0%

AC君温馨提醒

该题目为【codeforces】题库的题目,您提交的代码将被提交至codeforces进行远程评测,并由ACGO抓取测评结果后进行展示。由于远程测评的测评机由其他平台提供,我们无法保证该服务的稳定性,若提交后无反应,请等待一段时间后再进行重试。

题目描述

Inaka has a disc, the circumference of which is nn units. The circumference is equally divided by nn points numbered clockwise from 11 to nn , such that points ii and i+1i + 1 ( 1i<n1 \leq i < n ) are adjacent, and so are points nn and 11 .

There are mm straight segments on the disc, the endpoints of which are all among the aforementioned nn points.

Inaka wants to know if her image is rotationally symmetrical, i.e. if there is an integer kk ( 1k<n1 \leq k < n ), such that if all segments are rotated clockwise around the center of the circle by kk units, the new image will be the same as the original one.

输入格式

The first line contains two space-separated integers nn and mm ( 2n1000002 \leq n \leq 100\,000 , 1m2000001 \leq m \leq 200\,000 ) — the number of points and the number of segments, respectively.

The ii -th of the following mm lines contains two space-separated integers aia_i and bib_i ( 1ai,bin1 \leq a_i, b_i \leq n , aibia_i \neq b_i ) that describe a segment connecting points aia_i and bib_i .

It is guaranteed that no segments coincide.

输出格式

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).

输入输出样例

  • 输入#1

    12 6
    1 3
    3 7
    5 7
    7 11
    9 11
    11 3
    

    输出#1

    Yes
    
  • 输入#2

    9 6
    4 5
    5 6
    7 8
    8 9
    1 2
    2 3
    

    输出#2

    Yes
    
  • 输入#3

    10 3
    1 2
    3 2
    7 2
    

    输出#3

    No
    
  • 输入#4

    10 2
    1 6
    2 7
    

    输出#4

    Yes
    

说明/提示

The first two examples are illustrated below. Both images become the same as their respective original ones after a clockwise rotation of 120120 degrees around the center.

首页