#include <fstream>
#include <stack>
#include <vector>
#include <set>
#include <cstring>
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.*/