#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
#define nmax 100005

using namespace std;

ifstream fin("biconex.in");
ofstream fout("biconex.out");

int n, m;
vector <int> v[nmax];

void read() {
    int x, y;
    fin >> n >> m;
    for (int i = 1; i <= m; i++)
        fin >> x >> y,
        v[x].push_back(y),
        v[y].push_back(x);
}

int nrComp;
stack < pair<int, int> > s;
vector <int> comp[nmax];
int nivel[nmax], tata[nmax], low[nmax];
bool viz[nmax];

void newComp(int nod, int vc) {
    nrComp++;
    int x = s.top().first;
    int y = s.top().second;
    s.pop();
    while (x != nod && y != vc) {
        comp[nrComp].push_back(x);
        comp[nrComp].push_back(y);
        x = s.top().first;
        y = s.top().second;
        s.pop();
    }
    comp[nrComp].push_back(x);
    comp[nrComp].push_back(y);
}

void dfs(int nodCurent) {
    viz[nodCurent] = true;
    for (int i = 0; i < v[nodCurent].size(); i++) {
        int vecinCurent = v[nodCurent][i];
        if (!viz[vecinCurent]) {
            nivel[vecinCurent] = low[vecinCurent] = nivel[nodCurent] + 1;
            tata[vecinCurent] = nodCurent;
            s.push(make_pair(nodCurent, vecinCurent));
            dfs(vecinCurent);
            low[nodCurent] = min(low[nodCurent], low[vecinCurent]);
            if (low[vecinCurent] >= nivel[nodCurent]) {
                // componenta noua
                newComp(nodCurent, vecinCurent);
            }
        } else if (tata[nodCurent] != vecinCurent)
            low[nodCurent] = min(low[nodCurent], nivel[vecinCurent]);
    }
}

void solve() {
    for (int i = 1; i <= n; i++)
        if (!viz[i])
            dfs(i);
    fout << nrComp << "\n";
    for (int i = 1; i <= nrComp; i++) {
        sort(comp[i].begin(), comp[i].end());
        for (int j = 1; j < comp[i].size(); j++)
            if (comp[i][j-1] != comp[i][j])
                fout << comp[i][j-1] << " ";
        fout << comp[i][comp[i].size()-1] << "\n";
    }
}

int main() {

    read();
    solve();

    fin.close();
    fout.close();

    return 0;
}