#include <fstream>
#include <iostream>
#include <vector>
#include <stack>
using namespace std;
const int MAX = 100001;
vector <int> gr[MAX], sol[MAX];
stack <pair<int, int> > s;
int n, m, tata[MAX], low[MAX], niv[MAX], nsol, aux[MAX];
ifstream fin("biconex.in");
ofstream fout("biconex.out");
void dfs(int nod, int lev)
{
    low[nod] = niv[nod] = lev;
    for(unsigned i=0; i<gr[nod].size(); i++){
        int fiu = gr[nod][i];
        if(tata[nod] == fiu) continue;
        if(niv[fiu]==0){
            s.push({nod, fiu});
            dfs(fiu, lev+1);
            if(low[nod]>low[fiu]) low[nod] = low[fiu];
            if(low[fiu]>=lev){
                nsol++;
                int gata = 0;
                while(!gata){
                    int a = s.top().first, b = s.top().second;
                    s.pop();
                    if(a == nod and b == fiu) gata = 1;
                    if(aux[a]!=nsol) sol[nsol].push_back(a);
                    if(aux[b]!=nsol) sol[nsol].push_back(b);
                    aux[a] = aux[b] = nsol;
                }
            }
        }
        else
            if(low[nod]>niv[fiu]) low[nod] = niv[fiu];
    }
}
int main()
{
    fin>>n>>m;
    for(int i=1; i<=m; i++){
        int x, y;
        fin>>x>>y;
        gr[x].push_back(y);
        gr[y].push_back(x);
    }
    dfs(1, 1);
    fout<<nsol<<'\n';
    for(int i=1; i<=nsol; i++){
        for(unsigned j = 0; j<sol[i].size(); j++)
            fout<<sol[i][j]<<' ';
        fout<<'\n';
    }
    return 0;
}