1WA3RE

#include<bits/stdc++.h>
using namespace std;
const int N=2e4+7;
const int M=1e5+7;
struct edge{
	int nxt,v;
}e[M<<1];
int h[N],cnt=1;
void add_edge(int u,int v){
	e[++cnt].nxt=h[u],e[cnt].v=v;
	h[u]=cnt;
}
int dfn[N],low[N],tot,sum[N],st[N],top;
int n,m,ans;
void dfs(int u,int lst){
	dfn[u]=low[u]=++tot;
	st[++top]=u;
	for(int i=h[u];i;i=e[i].nxt){
		int v=e[i].v;
		if(i==(lst^1)) continue;//经测试，第四个测试点RE在这条语句？
		if(!dfn[v]){
			dfs(v,i);
			low[u]=min(low[u],low[v]);
			if(low[v]>=dfn[u]){
				sum[u]++;
				int vv;
				do sum[vv=st[top--]]++; while(u!=vv);
			}
		}else low[u]=min(low[u],dfn[v]);	
	}
}
int main(){
	freopen("P3388_4.in","r",stdin);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++){
		int u,v;
		scanf("%d%d",&u,&v);
		add_edge(u,v),add_edge(v,u);
	}
	for(int i=1;i<=n;i++)
		if(!dfn[i]) top=0,dfs(i,0);
	for(int i=1;i<=n;i++)
		ans+=sum[i]>1;
	printf("%d\n",ans);
	for(int i=1;i<=n;i++)
		if(sum[i]>1) printf("%d ",i);
	return 0;
}