Problem3407--【Div2】图论练习 - abc404c-Cycle Graph?

3407: 【Div2】图论练习 - abc404c-Cycle Graph?

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Time Limit : 1.000 sec  Memory Limit : 128 MB

SubmitSolved: 8Submit Num: 17Statistics

Description




Sample Input Copy 

4 4
2 4
3 1
4 1
2 3

Sample Output Copy 

Yes

HINT

Source/Category

Div2 图论 并查集 数据结构 
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