Given a simple, undirected graph with $n$ vertices and $m$ edges,. Find all articulation points.
### Input
- The first line contains 2 integers $n,m$.
- The next $m$ lines, each line contains two integers $u, v$, there is an edge between $u$ and $v$.
### Output
- The first line, print the number of articulation points, the second line print the articulation points in ascending order.
### Constraints
- $1 \le n,m \le 10^5$.
- $1 \le u,v \le n$.
### Example
Input:
```
6 5
1 3
2 3
3 4
4 5
4 6
```
Output:
```
2
3 4
```