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EISPGRH - Question 1

You are given an undirected graph that has n vertices and m edges. You should check if the given graph is a simple graph.

Input

The first line contains two integers n, m (0 < n, m ≤ 105).

Each of the next m lines contains two integers a, b representing an edge that connects vertex a and vertex b (0 ≤ a, b < n).

Output

Print “YES” if the given graph is a simple graph, otherwise print “NO”. The output is case-sensitive.

Sample

https://drive.google.com/file/d/1N1-NJnSAq7MrNJ9Oy3_f5en2PyOVNKd1/view?usp=sharing

Input

Output

 

Input

Output

5 4

0 0

0 1

1 2

2 1

NO

 

5 4

0 1

1 2

2 3

0 3

YES
Submit solution!
Added by:Ha Minh Ngoc
Date:2021-07-11
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: GOSU
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