#include <fstream>

using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
#define nmax 100005
struct nod
{
    int val;
    nod *urm;
};
struct segment
{
    int x,y;
};
segment st[nmax];
typedef nod *pnod;

pnod v[nmax],p;
void ad(int x,int y)
{
    p=new nod;
    p->val=y;
    p->urm=v[x]->urm;
    v[x]->urm=p;
}
int t[nmax],ind[nmax],mind[nmax],index,ss,cate,fiind,fi[nmax],n,m;
void bic(int i)
{
    index+=1;
    ind[i]=mind[i]=index;
    ss+=1;
    st[ss].x=i;
    pnod p=v[i]->urm;
    while(p)
    {
        if(ind[p->val]==0)
        {
            t[p->val]=i;
            st[ss].y=p->val;
            bic(p->val);
            mind[i]=min(mind[i],mind[p->val]);
            if(ind[i]<=mind[p->val])
            {
                cate+=1;
                while(st[ss].x!=i and st[ss].y!=p->val)
                {
                    fiind+=1;
                    fi[fiind]=st[ss].x;
                    ss-=1;
                }
                fiind+=1;
                fi[fiind]=i;
                fiind+=1;
            }
        }
        else
            if(t[i]!=p->val)
                mind[i]=min(mind[i],ind[p->val]);
        p=p->urm;
    }
}
int main()
{
    int i,x,y;
    f>>n>>m;
    for(i=1;i<=n;i++)
    {
        v[i]=new nod;
        v[i]->urm=0;
    }
    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        ad(x,y);
        ad(y,x);
    }
    for(i=1;i<=n;i++)
    {
        if(ind[i]==0)
        {
            index=0;
            ss=0;
            bic(i);
        }
    }
    g<<cate<<'\n';
    for(i=1;i<=fiind;i++)
    {
        while(fi[i]!=0)
        {g<<fi[i]<<" ";i++;}
        g<<'\n';
    }
    return 0;
}