#include <bits/stdc++.h>

using namespace std;

ifstream fin("biconex.in");
ofstream fout("biconex.out");
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<int>& discovery_time,vector<int>& lowest_reachable,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<int>& discovery_time,vector<int>& lowest_reachable,int& timer){
    discovery_time[vertex] = lowest_reachable[vertex] = ++timer;
    for(int neighbor : adjacency_list[vertex]){
        vertices_stack.push(vertex);
        if(neighbor != parent[vertex]) {
            if (parent[neighbor] == -1) {
                parent[neighbor] = vertex;
                BCC(neighbor, parent, vertices_stack, discovery_time,lowest_reachable, timer);
                lowest_reachable[vertex] = min(lowest_reachable[neighbor], lowest_reachable[vertex]);
                if (discovery_time[vertex] <= lowest_reachable[neighbor]) {
                    unordered_set<int> component;
                    component.insert(vertex);
                    int temp = vertices_stack.top();
                    while(temp!=vertex){
                        if(component.find(temp)==component.end())
                            component.insert(temp);
                        vertices_stack.pop();
                        temp = vertices_stack.top();
                    }
                    biconnected_components.push_back(component);
                }
            }
            else {
                lowest_reachable[vertex] = min(discovery_time[neighbor], lowest_reachable[vertex]);
            }
        }
    }
}



#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<int> discovery_time(vertices+1,-1);
    vector<int> lowest_reachable(vertices+1,-1);

    int timer = 0;

    parent[1] = 1;
    BCC(1,parent,vertices_stack,discovery_time,lowest_reachable,timer);

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

#pragma endregion