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

void newComp(int nod, int vecin) {
    nrComp++;
    int x = s.top().first;
    int y = s.top().second;
    s.pop();
    while (x != nod && y != vecin) {
        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] = 1;
    for (int i = 0; i < G[nodCurent].size(); i++) {
        int vecinCurent = G[nodCurent][i];
        if (!viz[vecinCurent]) {
            nivel[vecinCurent] = nivel[nodCurent] + 1;
            low[vecinCurent] = nivel[vecinCurent];
            tata[vecinCurent] = nodCurent;
            s.push(make_pair(nodCurent, vecinCurent));
            dfs(vecinCurent);
            low[nodCurent] = min(low[nodCurent], low[vecinCurent]);
            if (low[vecinCurent] >= nivel[nodCurent])
                newComp(nodCurent, vecinCurent);
        } else if (tata[nodCurent] != vecinCurent) {
            low[nodCurent] = min(low[nodCurent], nivel[vecinCurent]);
        }
    }
}

int main() {
    
    fin >> n >> m;
    
    for (int i = 1; i <= m; i++) {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    
    dfs(1);
    
    fout << nrComp << "\n";
    
    for (int i = 1; i <= nrComp; i++) {
        sort(comp[i].begin(), comp[i].end());
        fout << comp[i][0] << " ";
        for (int j = 1; j < comp[i].size(); j++)
            if (comp[i][j] != comp[i][j-1])
                fout << comp[i][j] << " ";
        fout << "\n";
    }
    
    fin.close();
    fout.close();
    
    return 0;
}