#include <iostream>
#include <vector>
#include <algorithm>
#include <fstream>
#include <deque>

using namespace std;

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

#define nmax 100005

int n, m, Min[nmax], nivel[nmax], t[nmax];
bool viz[nmax];
deque< pair<int,int> > dq;
vector<int> Comp[nmax], gf[nmax];
int comp = 0;

void citeste(){
    f >> n >> m;
    int x, y;
    for(int i=1; i<=m; ++i){
        f >> x >> y;
        gf[x].push_back(y);
        gf[y].push_back(x);
    }
}

void bagaComp(int nod, int vc){
    ++comp; // apare o noua componenta
    int X = dq.back().first; int Y = dq.back().second;
    dq.pop_back();
    while( (X != nod || Y != vc) && ( X != vc || Y != nod ) ){
        Comp[comp].push_back(X); Comp[comp].push_back(Y);
        X = dq.back().first; Y = dq.back().second;
        dq.pop_back();
    }
    Comp[comp].push_back(X); Comp[comp].push_back(Y);
}

void dfs(int nod){
    viz[nod] = 1;
    for(int i=0; i<gf[nod].size(); ++i){
        int vc = gf[nod][i];
        if (viz[vc] == 0){
            t[vc] = nod;
            nivel[vc] = nivel[nod] + 1;
            Min[vc] = nivel[vc];// initial
            dq.push_back( make_pair(nod, vc) );
            dfs(vc);
            Min[nod] = min(Min[nod], Min[vc]);
            if (Min[vc] >= nivel[nod]){// => pot ajune pana in nod maxim daca il scot
            // pe nod nu o sa mai pot ajunge in vc
                bagaComp(nod, vc);
            }
        }else if (t[vc] != nod){// ma duc din nod in vc (asta fiind o muchie de intoarcere)
            Min[nod] = min(Min[nod], nivel[vc]);// am voie sa ma duc pe maxim o muchie de intoarcere
        }
    }
}

void rezolva(){
    for(int i=1; i<=n; ++i){
        if (viz[i] == 0)
            dfs(i);
    }

    g << comp << "\n";
    for(int i=1; i<=comp; ++i){
        sort(Comp[i].begin(), Comp[i].end() );
        for(int j=1; j<Comp[i].size(); ++j){
            if (Comp[i][j] != Comp[i][j-1]){
                g << Comp[i][j-1] << " ";
            }
        }
        g << Comp[i][ Comp[i].size()-1 ] << "\n";
    }
}

int main(){
    citeste();
    rezolva();

    f.close();
    g.close();

    return 0;
}