#include <fstream>
#include <vector>
#include <deque>
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
const int lim=100005;
int n,m,i,j,nrfii,tati[lim],vf[lim],l[lim],c[lim],rad,nivel[lim],cerinta,nr,nr2;
vector<int>lv[lim],bi[lim];
vector<int>v;
pair<int,int>p[lim];
deque<int>s;
void dfs(int nod)
{
    vf[nod]=1;
    s.push_front(nod);
    l[nod]=nivel[nod];
    for(unsigned int j=0;j<lv[nod].size();j++)
    {
        int vecin=lv[nod][j];
        if(!vf[vecin])
        {
            nivel[vecin]=nivel[nod]+1;
            tati[vecin]=nod;
            if(nod==rad)nrfii++;
            dfs(vecin);
            if(l[nod]>l[vecin])
                l[nod]=l[vecin];
            if(l[vecin]>=nivel[nod])c[nod]=1;
            if(l[vecin]>nivel[nod])
                p[++nr]=make_pair(nod,vecin);
             if(nivel[nod]<=l[vecin])
             {nr2++;
                 while(s.front()!=vecin)
                 {
                bi[nr2].push_back(s.front());
                 s.pop_front();
                 }
             bi[nr2].push_back(vecin);
             s.pop_front();
             bi[nr2].push_back(nod);
             }
        }
        else
            if(vecin!=tati[nod] && l[nod]>nivel[vecin])
            l[nod]=nivel[vecin];
    }
}
int main()
{cerinta=1;
    f>>n>>m;
for(int i=1;i<=m;i++)
{
   int x,y;
   f>>x>>y;
   lv[x].push_back(y);
   lv[y].push_back(x);
}
for(int i=1;i<=n;i++)
    if(!vf[i])
{
    nivel[i]=1;
    rad=i;
    nrfii=0;
    dfs(i);
    if(nrfii>1)
        c[i]=1;
    else
        c[i]=0;
}
if(cerinta==2)
{
    for(int i=1;i<=n;i++)
    if(c[i])
    v.push_back(i);
g<<v.size()<<'\n';
   for(size_t j=0;j<v.size();j++)
    g<<v[j]<<" ";

}
if(cerinta==3)
{
    g<<nr<<"\n";
    for(int i=1;i<=nr;i++)
        g<<p[i].first<<" "<<p[i].second<<"\n";
}
if(cerinta==1)
{
    g<<nr2<<endl;
for(int i=1;i<=nr2;i++)
{
    for(size_t j=0; j<bi[i].size();j++)
        g<<bi[i][j]<<" ";
    g<<endl;
}
}

    return 0;
}