#include <bits/stdc++.h>

using namespace std;

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

struct Tracker{
    int discovery_time;
    int lowest_reachable;
    Tracker(int d = 0,int l = 0):discovery_time(d),lowest_reachable(l){ }
};

class Graph {

private:

    //Variabile private

    int vertices;
    int edges;
    bool oriented;
    vector<int> *adjacency_list;

    //To compute:
    vector<unordered_set<int>> biconnected_components;

    //Functii private

    void BFS(int starting_vertex, int *distances);

    void DFS(int vertex,int* visited);

    void BCC(int vertex,vector<int>& parent, stack<int>& vertices_stack, vector<Tracker>& tracker,int& timer);

public:

    Graph(int vertices = 0, int edges = 0, bool oriented = false);

    ~Graph();

    void infoarena_graph();

    void show_my_graph();

    void solve_distances(int starting_vertex);

    void solve_connected_components();

    void solve_biconnected();

};

int main() {
    int N,M;

    fin>>N>>M;

    Graph g(N,M, false);
    g.infoarena_graph();

    g.solve_biconnected();

}


#pragma region Initialization
Graph::Graph(int vertices, int edges, bool oriented) : vertices(vertices), edges(edges), oriented(oriented) {
    adjacency_list = new vector<int>[vertices + 1];
}

Graph::~Graph() {
    delete[] adjacency_list;
}

void Graph::infoarena_graph() {
    int x, y;
    if (oriented) {
        for (int i = 1; i <= edges; i++) {
            fin >> x >> y;
            adjacency_list[x].push_back(y);
        }
    } else {
        for (int i = 1; i <= edges; i++) {
            fin>>x>>y;
            adjacency_list[x].push_back(y);
            adjacency_list[y].push_back(x);
        }
    }
}

void Graph::show_my_graph() {
    for(int i = 1;i<vertices+1;i++){
        cout<<i<<"=>";

        for(int j : adjacency_list[i]){
            cout<<j<<' ';
        }
        cout<<'\n';
    }
}

#pragma endregion

//Algorithm implementations
#pragma region Algorithms

void Graph::BFS(int starting_vertex, int *distances) {

    int* visited = (int*) calloc(vertices+1,sizeof (int));
    queue<int> que;
    que.push(starting_vertex);

    distances[starting_vertex] = 1;
    visited[starting_vertex] = 1;

    while (!que.empty()) {
        int current_node = que.front();
        que.pop();

        for (auto neighbor : adjacency_list[current_node]) {
            if (!visited[neighbor]) {
                que.push(neighbor);
                visited[neighbor] = 1;
                distances[neighbor] = distances[current_node] + 1;
            }
        }
    }

    free(visited);
}

void Graph::DFS(int vertex, int *visited) {

    visited[vertex] = 1;

    for(auto neighbor : adjacency_list[vertex])
        if(!visited[neighbor])
            DFS(neighbor,visited);
}

void Graph::BCC(int vertex,vector<int>& parent, stack<int>& vertices_stack, vector<Tracker>& tracker,int& timer){

    tracker[vertex].discovery_time = tracker[vertex].lowest_reachable = ++timer;

    for(int neighbor : adjacency_list[vertex]){
        //Not visited yet;
        vertices_stack.push(vertex);

        if(parent[neighbor]==-1){
            parent[neighbor] = vertex;
            BCC(neighbor,parent,vertices_stack,tracker,timer);

            tracker[vertex].lowest_reachable = min(tracker[neighbor].lowest_reachable,tracker[vertex].lowest_reachable);

            if(tracker[vertex].discovery_time <= tracker[neighbor].lowest_reachable){
                int aux;
                biconnected_components.push_back(unordered_set<int>());
                int n = biconnected_components.size();
                aux = vertices_stack.top();
                while(aux!=vertex){
                    biconnected_components[n-1].insert(aux);
                    vertices_stack.pop();
                    aux = vertices_stack.top();
                }
                biconnected_components[n-1].insert(aux);
            }
        }
        else{
            tracker[vertex].lowest_reachable = min(tracker[neighbor].discovery_time, tracker[vertex].lowest_reachable);
        }
    }
}



#pragma endregion


//infoarena solutions
#pragma region Solutions

//Minimal distances BFS problem
void Graph::solve_distances(int starting_vertex) {
    int *distances = (int*)calloc(vertices+1,sizeof (int));

    BFS(starting_vertex,distances);

    for(int i = 1;i<vertices+1;i++)
        fout<<distances[i] - 1<<' ';

    free(distances);
}

//Connected compontents DFS problem
void Graph::solve_connected_components() {

    int counter = 0;
    int* visited = (int*)calloc(vertices+1,sizeof (int));

    for(int i = 1;i<vertices + 1;i++)
        if(!visited[i]){
            DFS(i,visited);
            counter++;
        }

    fout<<counter;
    free(visited);
}

void Graph::solve_biconnected() {

    stack<int> vertices_stack;
    vector<int> parent(vertices+1,-1);
    vector<Tracker> tracker(vertices+1,(0,0));

    int timer = 0;

    for(int i = 1;i<vertices+1;i++){
        if(parent[i] == -1){
            parent[i] = i;
            BCC(i,parent,vertices_stack,tracker,timer);
        }
    }

    fout<<biconnected_components.size()<<'\n';
    for(auto components : biconnected_components){
        for (auto i : components)
            fout<<i<<' ';
        fout<<'\n';
    }
}

#pragma endregion