# include <fstream>
# include <vector>
# include <algorithm>
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
vector <int> v[100000], sol[100000];
struct elem
{
    int x,y;
}st[200005],E;
int i,j,x,y,n,m,VV,nrsol;
int low[100005],niv[100005],ap[100005];
void DFS (int k, int nivel, int parinte)
{
    int i,ok;
    niv[k]=nivel; low[k]=nivel; ap[k]=1;
    for (i=0; i<v[k].size(); ++i)
    {
        ok=0;
        if (v[k][i]!=parinte)
        {
            if (! ap[v[k][i]])
            {
                E.x=k; E.y=v[k][i];
                st[++VV]=E; ok=1;
                DFS(v[k][i],nivel+1,k);
            }
            low[k]=min(low[k], low[v[k][i]]);
            if (ok && low[v[k][i]]>=nivel)
            {
                sol[++nrsol].push_back(st[VV].y);
                --VV;
                while (VV && st[VV].x!=k)
                    sol[nrsol].push_back(st[VV].y),--VV;
                sol[nrsol].push_back(st[VV].y);
                sol[nrsol].push_back(k); --VV;
            }
        }
    }
}
int main ()
{
    f>>n>>m;
    for (i=1; i<=m; ++i)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    DFS(1,1,0);
    g<<nrsol<<"\n";
    for (i=1; i<=nrsol; ++i)
    {
        for (j=0; j<sol[i].size(); ++j)
            g<<sol[i][j]<<" ";
        g<<"\n";
    }
    return 0;
}