#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;

set <int> aux[Nmax];

int lvl[Nmax],Low[Nmax];

int n,m,x,y,nrcomp;

static inline void delstec(int v,int w)

{

    int f,s;

    while(1)

    {

        f = stec.top().first;

        s = stec.top().second;

        aux[nrcomp].insert(f);

        aux[nrcomp].insert(s);

        stec.pop();

        if(f == v && s == w)
            break;

    }

}

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;

    memset(lvl,-1,sizeof(lvl));

    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])

            out << j << " ";

        out << '\n';

    }

    return 0;

}
/** sursa lui Ionita Daniel. Nu imi apartine.*/