#include <bits/stdc++.h>

using namespace std;

ifstream fin("biconex.in");
ofstream fout("biconex.out");

int N,M,nrC;
int Niv[100005],NivMin[100005];
bool Viz[100005];
vector<int>Ad[100005],Comp[100005];
stack<int>S;

void citire()
{
    int x,y;
    fin>>N>>M;
    for(int i=1;i<=M;i++)
    {
        fin>>x>>y;
        Ad[x].push_back(y);
        Ad[y].push_back(x);
    }
}

void compBicon(int vf)
{
    nrC++;
    while(S.top()!=vf)
    {
        Comp[nrC].push_back(S.top());
        S.pop();
    }
    S.pop();
}

void DFS(int vf,int tata)
{
    Niv[vf]=NivMin[vf]=Niv[tata]+1;
    Viz[vf]=1;
    S.push(vf);
    for(unsigned i=0;i<Ad[vf].size();i++)
    {
        if(Viz[Ad[vf][i]])
            NivMin[vf]=min(NivMin[vf],Niv[Ad[vf][i]]);
        else
        {
            DFS(Ad[vf][i],vf);
            NivMin[vf]=min(NivMin[vf],NivMin[Ad[vf][i]]);
            if(NivMin[Ad[vf][i]]>=Niv[vf])
            {
                compBicon(Ad[vf][i]);
                Comp[nrC].push_back(vf);
                Comp[nrC].push_back(Ad[vf][i]);
            }
        }
    }
}

void afisare()
{
    fout<<nrC<<'\n';
    for(int i=1;i<=nrC;i++)
    {
        for(unsigned j=0;j<Comp[i].size();j++)
            fout<<Comp[i][j]<<" ";
        fout<<'\n';
    }
}

int main()
{
    citire();
    DFS(1,0);
    afisare();
    return 0;
}