割点-模板

#include<bits/stdc++.h>
using namespace std;
//input by bxd
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define repp(i,a,b) for(int i=(a);i>=(b);--i)
#define RI(n) scanf("%d",&(n))
#define RII(n,m) scanf("%d%d",&n,&m)
#define RIII(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define RS(s) scanf("%s",s);
#define ll long long
#define pb push_back
#define REP(i,N)  for(int i=0;i<(N);i++)
#define CLR(A,v)  memset(A,v,sizeof A)
//////////////////////////////////
#define inf 0x3f3f3f3f
const int N=100010;
const int M=10*N;
 int n,m;
int pos,head[M];
struct Edge
{
    int to,nex;
}edge[M];
void add(int a,int b)
{
    edge[++pos].nex=head[a];
    head[a]=pos;
    edge[pos].to=b;
}
int dfn[N],tot,low[N],cut[N];
void init()
{
    tot=pos=0;
    CLR(head,0);
    CLR(dfn,0);
    CLR(cut,0);
}
void tarjan(int x,int fa)
{
    dfn[x]=low[x]=++tot;
    int son=0;
    for(int i=head[x];i;i=edge[i].nex)
    {
        int v=edge[i].to;
        if(!dfn[v])
        {
            tarjan(v,fa);
            low[x]=min(low[x],low[v]);
            if(low[v]>=dfn[x]&&x!=fa)
                cut[x]=1;
            if(v==fa)
                son++;
        }
        low[x]=min(low[x],dfn[v]);

    }
    if(son>=2&&x==fa)
        cut[x]=1;
}
int main()
{
    int n,m;
    RII(n,m);
    init();
    rep(i,1,m)
    {
        int a,b;RII(a,b);
        add(a,b);add(b,a);
    }
    rep(i,1,n)
    if(!dfn[i])
        tarjan(i,i);
    int cnt=0;

    rep(i,1,n)
    if(cut[i])
        cnt++;
    cout<<cnt<<endl;

    rep(i,1,n)
    if(cut[i])
        cout<<i<<" ";
}