12pts求条

#include <bits/stdc++.h>
using namespace std;
const int N=4*1e4+10;
vector<int> tu[N];
int dfn[N],low[N],prt[N],cnt,tong[N];
int n,m;
int x,y,root;
vector<int> ans;
void Tarjan(int u){
	++cnt;
	low[u]=cnt;
	dfn[u]=cnt;
	for(int v:tu[u]){
		if(prt[u]!=v){
			if(dfn[v]==0){
				prt[v]=u;
				Tarjan(v);
				low[u]=min(low[u],low[v]);
				if(dfn[u]>1&&low[v]>=dfn[u]&&tong[u]==0){
					tong[u]=1;
					ans.push_back(u);
				}
				else if(dfn[u]==1){
					root++;
					if(root>=2&&tong[u]==0){
						tong[u]=1;
						ans.push_back(u);
					}
				}
			}
			else{
				low[u]=min(low[u],dfn[v]);
			}
		}
	}
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	for(int i=1;i<=m;i++){
		cin>>x>>y;
		tu[x].push_back(y);
		tu[y].push_back(x);
	}
	for(int i=1;i<=n;i++){
		if(dfn[i]==0) Tarjan(i);
	}
	cout<<ans.size()<<endl;
	sort(ans.begin(),ans.end());
	for(int i:ans) cout<<i<<" ";
	return 0;
}