#include <fstream>
#include <vector>
#include <stack>

#define pb push_back
#define Ndim 100005
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
int N,M,nrcbc,Low[Ndim],Lev[Ndim];
bool VIZ[Ndim];
vector <int> G[Ndim],CBC[Ndim];
stack <int> Stv;
void read()
{
    int i,a,b;
    fin>>N>>M;
    for(i=1;i<=M;i++)
    {
        fin>>a>>b;
        G[a].pb(b);
        G[b].pb(a);
    }
}
void DFS(int nod,int tata)
{
    VIZ[nod] = 1;
    Lev[nod] = Lev[tata] + 1;
    Low[nod] = Lev[nod];
    Stv.push(nod);
    for(size_t i = 0; i<G[nod].size();i++)
    {
        int vecin = G[nod][i];
        if(vecin == tata)
            continue;
        if(VIZ[vecin] == 1)
            Low[nod] = min(Low[nod],Lev[vecin]);
        else
        {
            DFS(vecin,nod);
            Low[nod] = min(Low[nod],Low[vecin]);
            if(Low[vecin] >= Lev[nod])
            {
                nrcbc++;
                CBC[nrcbc].pb(nod);
                int x;
                do
                {
                    CBC[nrcbc].pb(Stv.top());
                    x = Stv.top();
                    Stv.pop();
                }while(x!=vecin);
            }
        }
    }
}
void print()
{
    fout<<nrcbc<<'\n';
    for(int i=1;i<=nrcbc;i++)
    {
        for(size_t j=0;j<CBC[i].size();j++)
            fout<<CBC[i][j]<<' ';
        fout<<'\n';
    }
}
int main()
{
    read();
    DFS(1,0);
    print();
    return 0;
}