#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <fstream>
#include <algorithm>

using namespace std;

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

class Graph {
    std::vector<std::vector<int>> Ad;
    int nodes; // no of nodes
    int edges; // no of edges
    int directed; // 1 for directed
public:
    Graph(const std::vector<std::pair<int,int>> &ad, int nodes, int edges,int directed);
    int getComponents();
    void pathTo(int node);
    std::stack<int> topSort();
    void printSCC(); // print strongly connected components
    void printBCC(); //print biconex components

private:
    void DFS(int node, std::vector<int> &vis);
    void BFS(int node, std::vector<int> &vis);
    void topSortDFS(int node, std::vector<int> &vis, std::stack<int> &s);
    void dfsSCC(int node,int &idInc, std::vector<int> &id, std::vector<int> &low, std::vector<bool> &onStack, std::stack<int> &s, std::vector< std::vector<int>> &scc); // dfs for scc
    std::vector< std::vector<int>> getSCC(); // returns scc with tarjan
    void dfsBCC(int node, int parent, int &time, std::vector<int> &dq, std::vector<int> &low, std::vector<int> &disc, std::vector<std::vector<int>> &bcc);

};

Graph::Graph(const std::vector<std::pair<int,int>> &ad, int nodes, int edges, int directed) : nodes(nodes), edges(edges), directed(directed) {
    Ad.resize(nodes+1);
    for(int i = 0; i<edges; ++i){
        Ad[ad[i].first].push_back(ad[i].second);
        if(directed == 0)
            Ad[ad[i].second].push_back(ad[i].first);
    }
}

void Graph::DFS(int node, std::vector<int> &vis){
    vis[node] = 1;
    for(int i = 0; i<Ad[node].size(); ++i)
        if(vis[Ad[node][i]] == 0){
            DFS(Ad[node][i], vis);
        }
}

int Graph::getComponents() {
    std::vector<int> vis;
    int ct = 0;
    vis.resize(nodes);
    std::fill(vis.begin(), vis.end(), 0);
    for(int i = 1;i <= nodes; ++i)
        if(vis[i] == 0){
            DFS(i, vis);
            ct++;
        }
    return ct;
}

void Graph::BFS(int node, std::vector<int> &vis){
    int parent, distance;
    std::queue<int> Q;
    Q.push(node);
    vis[node] = 0;
    while(!Q.empty()){
        parent = Q.front();
        Q.pop();
        for(int i = 0; i<Ad[parent].size(); ++i)
            if(vis[Ad[parent][i]] == -1){
                Q.push(Ad[parent][i]);
                vis[Ad[parent][i]] = vis[parent] + 1;
            }
    }
}

void Graph::pathTo(int node){
    std::vector<int> vis;
    vis.resize(nodes+1);
    std::fill(vis.begin(), vis.end(), -1);
    vis[node] = 0;
    BFS(node, vis);
    for(int i = 1; i<= nodes; ++i)
        fout << vis[i]<< " ";
}

void Graph::topSortDFS(int node, std::vector<int> &vis, std::stack<int> &s){
    vis[node] = 1;
    for(int i = 0; i<Ad[node].size(); ++i)
        if(vis[Ad[node][i]] == 0)
            topSortDFS(Ad[node][i], vis, s);
    s.push(node);
}

std::stack<int> Graph::topSort(){
    std::vector<int> vis;
    std::stack<int> s;
    vis.resize(nodes+1);
    std::fill(vis.begin(), vis.end(), 0);
    for(int i = 1; i<=nodes; ++i)
        if(!vis[i])
           topSortDFS(i, vis, s);
    return s;
}

void HavelHakimi(){
    std::vector<int> v;
    int n,x, val; // val - deleted value in havel hakimi
    bool hh = true; //check if havel hakimi conditions are still met
    fin >> n;
    for(int i = 0; i<n; ++i){
        fin >> x;
        v.push_back(x);
    }
    while(true){
        sort(v.begin(), v.end(), greater<>());

        if(v[0] == 0)
            break;
        val = v[0];
        v.erase(v.begin());
        if(v.size() < val){
            hh = false;
            break;
        }
        for(int i = 0; i<val; ++i){
            v[i]--;
            if(v[i] < 0){
                hh = false;
                break;
            }
        }
    }
    if( hh == true )
        std::cout << "Simple graph.";
    else std::cout << "Not a simple graph.";

}

void Graph::dfsSCC(int node,int &idInc, std::vector<int> &id, std::vector<int> &low, std::vector<bool> &onStack, std::stack<int> &s, std::vector< std::vector<int>> &scc){
    int nod;
    s.push(node);
    onStack[node] = true;
    id[node] = low[node] = idInc++;
    for(int i = 0; i<Ad[node].size(); ++i){
        int next = Ad[node][i];
        if(id[next] == 0)
            dfsSCC(next, idInc, id, low, onStack, s, scc);
        if(onStack[next] == true)
            low[node] = min(low[node], low[next]);
    }
    if(id[node] == low[node]){
        std::vector<int> comp; ///next component in scc vector
        while(!s.empty()){
            nod = s.top();
            s.pop();
            onStack[nod] = false;
            comp.push_back(nod);
            low[nod] = id[node];
            if(nod == node)
                break;
        }
        scc.push_back(comp);
    }
}

std::vector< std::vector<int>> Graph::getSCC(){
    int idInc = 1; //increment node id
    std::vector<int> id(nodes+1);
    std::vector<int> low(nodes+1);
    std::vector<bool> onStack(nodes+1, 0);
    std::vector< std::vector<int>> scc; //vector of components
    std::stack<int> s;
    for(int i = 1; i<=nodes; ++i)
        id[i] = low[i] = 0;
    for(int i = 1; i<=nodes; ++i)
        if(id[i] == 0)
            dfsSCC(i,idInc, id, low, onStack, s, scc);
    return scc;
}

void Graph::printSCC(){
    std::vector< std::vector<int>> scc;
    scc = getSCC();
    fout << scc.size() << "\n";
    for(int i = 0; i<scc.size(); ++i){
        for(int j = 0; j<scc[i].size(); ++j)
            fout << scc[i][j] << " ";
        fout << "\n";
    }
}

void Graph::dfsBCC(int node, int parent, int &time, std::vector<int> &dq, std::vector<int> &low, std::vector<int> &disc, std::vector<std::vector<int>> &bcc){
    int w;
    disc[node] = low[node] = ++time;
    for(int i = 0; i<Ad[node].size(); ++i){

        w = Ad[node][i];

        if(w == parent)
            continue;

        if(disc[w] != 0)
            low[node] = min(low[node], disc[w]);

        else{
            dq.push_back(w);
            dfsBCC(w, node, time, dq, low, disc, bcc);

            low[node] = min(low[w], low[node]);

            if(low[w] >= disc[node]){
                dq.push_back(node);
                std::vector<int> nextComp;
                while(!dq.empty()){
                    int next = dq.back();
                    dq.pop_back();
                    nextComp.push_back(next);
                    if(next == w)
                        break;
                }
                bcc.push_back(nextComp);
            }
        }
    }

}

void Graph::printBCC(){
    int time = 0;
    std::vector<std::vector<int>> bcc;
    std::vector<int> dq; ///deque for components in next bcc
    std::vector<int> low(nodes), disc(nodes);
    dfsBCC(1,0,time, dq, low, disc, bcc);
    fout << bcc.size() << "\n";
    for(int i = 0; i<bcc.size(); ++i){
        for(int j = 0; j<bcc[i].size(); ++j)
            fout << bcc[i][j] << " ";
        fout << "\n";
    }
}

int main() {
    std::vector<std::pair<int,int>> Ad;
    std::stack<int> s;
    int n,m,x,y;
    fin >> n >> m;
    for(int i = 0; i<m; ++i){
        fin >> x >> y;
        Ad.push_back({x,y});
    }
    Graph G(Ad,n ,m, 0);
    G.printBCC();
    return 0;
}