#include <bits/stdc++.h>

using namespace std;

ifstream f("biconex.in");
ofstream g("biconex.out");

const int N = 1e5 + 1;
int n, m, x, y, t[N], tmin[N], timp, cnt;
vector<int> c[N], cbc[N];
stack<pair<int, int>> stiva;

void adaugaCBC(pair<int, int> e){
    vector<int> comp;
    while(stiva.top().first != e.first || stiva.top().second != e.second){
        comp.push_back(stiva.top().first);
        comp.push_back(stiva.top().second);
        stiva.pop();
    }

    comp.push_back(e.first);
    comp.push_back(e.second);
    stiva.pop();
    sort(comp.begin(), comp.end());
    cbc[++cnt].push_back(comp[0]);
    for(size_t i = 1; i < comp.size(); i++){
        if(comp[i] != comp[i - 1])
            cbc[cnt].push_back(comp[i]);
    }
}

void dfs(int nod, int tata = 0){
    t[nod] = tmin[nod] = ++timp; // trb. anumite chestii schimbate ca sa mearga timp++
    for(int y: c[nod]){
        if(t[y] == 0){
            stiva.push({nod, y});
            dfs(y, nod);
            tmin[nod] = min(tmin[nod], tmin[y]);
            if(tmin[y] >= t[nod])
                adaugaCBC({nod, y});
        }else if(y != tata)
            tmin[nod] = min(tmin[nod], t[y]);
    }
}

int main(){
    f >> n >> m;
    for(int i = 0; i < m; i++){
        f >> x >> y;
        c[x].push_back(y);
        c[y].push_back(x);
    }

    f.close();
    for(int i = 1; i <= n; i++){
        if(t[i] == 0)
            dfs(i);
    }

    g << cnt << '\n';
    for(int i = 1; i <= cnt; i++){
        for(int x: cbc[i])
            g << x << ' ';

        g << '\n';
    }

    g.close();
}