#include <iostream>
#include <fstream>
#include <vector>
#include <set>
#include <stack>
#include <algorithm>
#include <queue>
using namespace std;

ifstream f("biconex.in");
ofstream g("biconex.out");

vector <int> Q[100001];
vector<int> Z1,Z2;
stack<pair<int, int> >Z3;
vector< vector < int > >QQ;

int n,m,nrcomp;

void afisare(int cn1,int cn2)
{
    vector<int>Z4;
    int cnod1,cnod2;
    do
    {
        cnod1=Z3.top().first,cnod2=Z3.top().second;
        Z4.push_back(cnod1),Z4.push_back(cnod2);
        Z3.pop();
    }
    while(cnod1!=cn1||cnod2!=cn2);
    QQ.push_back(Z4);
    ++nrcomp;
}

void dfs(int nod,int tata,int numar)
{
    Z1[nod]=Z2[nod]=numar;
    for (vector<int>::iterator it=Q[nod].begin(); it!=Q[nod].end(); ++it)
    {
        if (*it==tata)continue;
        if (Z1[*it]==-1)
        {
            Z3.push(make_pair(nod,*it));
            dfs(*it,nod,numar+1);
            Z2[nod]=min(Z2[nod],Z2[*it]);
            if (Z2[*it]>=Z1[nod])
                afisare(nod,*it);
        }
        else
            Z2[nod]=min(Z2[nod],Z1[*it]);
    }
}


void citire()
{
    int a,b;
    f>>n>>m;
    while (f>>a>>b)
    {
        Q[b].push_back(a);
        Q[a].push_back(b);
    }
}

int main()
{
    citire();
    Z1.resize(n+1);
    Z1.assign(n+1,-1);
    Z2.resize(n+1);
    dfs(1,0,0);
    g<<nrcomp<<'\n';
    for (int c=0;c<nrcomp;++c)
    {
        sort(QQ[c].begin(),QQ[c].end());
        QQ[c].erase(unique(QQ[c].begin(),QQ[c].end()),QQ[c].end());
        for (vector<int>::iterator it=QQ[c].begin();it!=QQ[c].end();++it)
            g<<*it<<' ';
        g<<'\n';
    }
    return 0;
}