#include <bits/stdc++.h>
using namespace std;
ifstream in("biconex.in");
ofstream out("biconex.out");
typedef pair < int, int > pii;
const int Nmax = 1e5 + 5;
vector <int> a[Nmax];
stack < pii > stec;
vector <int> aux[Nmax];
vector <int> lvl(Nmax,-1),Low(Nmax);
int n,m,x,y,nrcomp,mama;
static inline void delstec(int v,int w)
{
    int f,s;
    while(1)
    {
        f = stec.top().first;
        s = stec.top().second;
        aux[nrcomp].push_back(f);
        aux[nrcomp].push_back(s);
        stec.pop();
        if(f == v && s == w) break;
    }
    sort(aux[nrcomp].begin(),aux[nrcomp].end());
}
static inline void df(int nod, int parinte, int niv)
{
    lvl[nod] = Low[nod] = niv;
    for(auto i : a[nod])
    {
        if(i == parinte) // daca e tatal lui,
            continue;   //mergi mai departe

        if(lvl[i] == -1) // daca e nod nevizitat
        {
            stec.push({nod,i}); // adauga pe stiva muchiile
            df(i, nod, niv+1);

            Low[nod] = min(Low[i],Low[nod]); // nivelul min care poate fi atins
            if(lvl[nod] <= Low[i]) // daca nu poate ajunge mai sus
            {
                nrcomp++;
                delstec(nod,i);
            } // incepe distractia
        }
        else Low[nod] = min(lvl[i],Low[nod]);
    }
}
int main()
{
    in.tie(0);
    in >> n >> m;
    lvl.resize(n+1,-1);
    Low.resize(n+1);
    while(m--)
    {
        in >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    df(1,0,1);
    out << nrcomp << '\n';
    for(int i = 1; i <= nrcomp; ++i)
    {
        for(auto& j : aux[i])
        {
            if(*(&j + 1) != j)
                out << j << " ";
        }
        out << '\n';
    }
    return 0;
}