求助！！急！！

#include<bits/stdc++.h>
using namespace std;
struct Edge{
	int u,v,next;
}e[200005];
int n,m,tot,x,y,head[20005],ans=0,num[20005],low[20005],ind;
bool vis[20005];
inline void add(int u,int v)
{
	e[++tot].u=u;
	e[tot].v=v;
	e[tot].next=head[u];
	head[u]=tot;
}
void tarjan(int cur,int fa)
{
	int child=0;
	ind++;
	num[cur]=ind;
	low[cur]=ind;
	for(int i=head[cur];i!=-1;i=e[i].next)
	{
		if(num[e[i].v]==0)
		{
			child++;
			tarjan(e[i].v,cur);
			low[cur]=min(low[cur],low[e[i].v]);
			if((cur!=1&&low[e[i].v]>=num[cur])||(cur==1&&child==2))
			vis[cur]=true;
		}
		else
		if(e[i].v!=fa)
		low[cur]=min(low[cur],num[e[i].v]);
	}
}
int main()
{
	memset(head,-1,sizeof(head));
	memset(vis,false,sizeof(vis));
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;++i)
	{
		scanf("%d%d",&x,&y);
		add(x,y);
		add(y,x);
	}
	tarjan(1,1);
	for(int i=1;i<=n;++i)
	if(vis[i]) ans++;
	printf("%d\n",ans);
	for(int i=1;i<=n;++i)
	if(vis[i]) printf("%d ",i); 
	return 0;
}