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

using namespace std;

int n,m,nr;
vector<int>g[100003];
stack<int>s;
vector<int>sol[100003];
int niv[100003],llk[100003];

void citire()
{
    ifstream fin("biconex.in");
    fin>>n>>m;
    int x,y;
    for(int i=0;i<m;i++)
    {
        fin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
}

void dfs(int vf,int tata)
{
    niv[vf]=niv[tata]+1;
    s.push(vf);
    llk[vf]=niv[vf];
    for(auto &fiu:g[vf])
    {
        if(fiu==tata)
            continue;
        if(niv[fiu])
        {
            llk[vf]=llk[vf]<niv[fiu]?llk[vf]:niv[fiu];
            continue;
        }
        dfs(fiu,vf);
        llk[vf]=llk[vf]<llk[fiu]?llk[vf]:llk[fiu];
        if(niv[vf]<=llk[fiu])
        {
            int x;
            nr++;
            do
            {
                x=s.top();
                sol[nr].push_back(x);
                s.pop();
            }while(!s.empty()&&x!=fiu);
            sol[nr].push_back(vf);
        }
    }
}

void afisare()
{
    ofstream fout("biconex.out");
    fout<<nr<<"\n";
    for(int i=1;i<=nr;i++)
    {
        for(auto &j:sol[i])
            fout<<j<<" ";
        fout<<"\n";
    }
}

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