1 #include<cstdio>
2 #include<cstring>
3 #include<cmath>
4 #include<ctime>
5 #include<iostream>
6 #include<algorithm>
7 #include<queue>
8 #include<stack>
9 #include<set>
10 #define esp (1e-6)
11 #define inf (0x3f3f3f3f)
12 #define l(a) ((a)<<1)
13 #define r(a) ((a)<<1|1)
14 #define b(a) (1<<(a))
15 #define rep(i,a,b) for(int i=a;i<=(b);i++)
16 #define clr(a) memset(a,0,sizeof(a))
17 typedef long long ll;
18 typedef unsigned long long ull;
19 using namespace std;
20 int readint(){
21 int t=0,f=1;char c=getchar();
22 while(!isdigit(c)){
23 if(c=='-') f=-1;
24 c=getchar();
25 }
26 while(isdigit(c)){
27 t=(t<<3)+(t<<1)+c-'0';
28 c=getchar();
29 }
30 return t*f;
31 }
32 const int maxn=100009,maxm=200009;
33 struct edge{
34 int v;
35 edge*next;
36 }e[maxm],*pt=e,*fir[maxn];
37 int n,m,ans,dfstime,scccnt,size[maxn],pre[maxn],low[maxn],scc[maxn];
38 bool p[maxn];
39 void add(int u,int v){
40 pt->v=v;pt->next=fir[u];
41 fir[u]=pt++;
42 }
43 void addedge(int u,int v){
44 add(u,v);add(v,u);
45 }
46 stack<int>S;
47 void dfs(int x,int f){
48 int son=0;
49 pre[x]=low[x]=++dfstime;S.push(x);
50 for(edge*e=fir[x];e;e=e->next) if(e->v!=f){
51 if(!pre[e->v]){
52 son++;dfs(e->v,x);
53 low[x]=min(low[x],low[e->v]);
54 if(f!=-1&&low[e->v]>=pre[x]) p[x]=1;
55 }else if(!scc[e->v]) low[x]=min(low[x],pre[e->v]);
56 }
57 if(f==-1&&son>1) if(!p[x]) p[x]=1;
58 if(pre[x]==low[x]){
59 int t=-1;++scccnt;
60 while(t!=x){
61 t=S.top();S.pop();
62 scc[t]=scccnt;size[scccnt]++;
63 }
64 }
65 }
66 void tarjan(){
67 rep(i,1,n) if(!scc[i]) dfs(i,-1);
68 rep(i,1,n) if(p[i]) ans++;
69 cout<<ans<<endl;
70 rep(i,1,n) if(p[i]){
71 ans--;printf("%d",i);
72 putchar(ans?' ':'\n');
73 }
74 }
75 int main(){
76 //freopen("#input.txt","r",stdin);
77 //freopen("#output.txt","w",stdout);
78 n=readint();m=readint();
79 rep(i,1,m){
80 int U=readint(),V=readint();
81 addedge(U,V);
82 }
83 tarjan();
84 //fclose(stdin);
85 //fclose(stdout);
86 return 0;
87 }
