#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
#define NMAX 100001

using namespace std;

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

vector <int> v[NMAX], rez[NMAX];
stack <pair<int,int> > st;
pair<int,int> aux;

int n, m, r, nr, cont;
int viz[NMAX], t[NMAX], niv[NMAX], low[NMAX], sol[NMAX];

void DF(int x)
{
    int i, nod;

    viz[x]=1;
    low[x]=niv[x];

    for(i=0;i<v[x].size();++i){
        nod = v[x][i];

        if(nod!=t[x] && niv[x] > niv[nod]){
            st.push(make_pair(x, nod));

            if(!viz[nod]){
                niv[nod]=niv[x]+1;
                t[nod]=x;

                DF(nod);

                low[x]=min(low[x],low[nod]);

                if(low[nod]>=niv[x]){
                    ++cont;
                    do{
                        aux=st.top();

                        rez[cont].push_back(aux.first);
                        rez[cont].push_back(aux.second);
                        st.pop();
                    }
                    while( (aux.first!=x || aux.second!=nod) && (aux.second!=x || aux.first!=nod) );
                }
            }else if(nod != t[x]) low[x]=min(low[x],niv[nod]);
        }
    }
}

int main()
{
    int i, x, y, j;
    f>>n>>m;
    for(i=1;i<=m;++i){
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }

    viz[1]=1;
    niv[1]=1;
    DF(1);

    g<<cont<<'\n';
    for(i=1;i<=cont;++i){
        sort(rez[i].begin(), rez[i].end());

        g<<rez[i][0]<<" ";
        for(j=1;j<rez[i].size();++j)
            if(rez[i][j] != rez[i][j-1])
                g<<rez[i][j]<<" ";
        g<<'\n';
    }
return 0;
}