#include <fstream>
#include <vector>
#include <bitset>
#include <unordered_set>
#include <stack>

using namespace std;

ifstream cin("biconex.in");
ofstream cout("biconex.out");

int n, m;
vector<vector<int>> graph;
vector<int> time_in, low_time_in;
bitset<(int)(1e5 + 5)> vis;
stack<pair<int, int>> component_edges;
int counter = 0;
vector<unordered_set<int>> answer;

void handle_found_articulation_point(int n1, int n2) {
    int top_n1 = 0, top_n2 = 0;
    unordered_set<int> connected_component;
    while (top_n1 != n1 && top_n2 != n2) {
        top_n1 = component_edges.top().first;
        top_n2 = component_edges.top().second;
        component_edges.pop();
        connected_component.insert(top_n1);
        connected_component.insert(top_n2);
    }
    answer.push_back(connected_component);
 }

void dfs(int node, int parent) {
    vis[node] = 1;
    time_in[node] = low_time_in[node] = counter++;
    for (int neighbor : graph[node]) {
        if (!vis[neighbor]) {
            component_edges.push({node, neighbor});
            dfs(neighbor, node);
            low_time_in[node] = min(low_time_in[node], low_time_in[neighbor]);
            if (low_time_in[neighbor] >= time_in[node]) {
                handle_found_articulation_point(node, neighbor);
            }
        } else if (vis[neighbor] && neighbor != parent) {
            low_time_in[node] = min(low_time_in[node], time_in[neighbor]);
        }
    }
}

int main() {
    cin >> n >> m;
    graph.assign(n + 2, vector<int>());
    time_in.assign(n + 2, 0);
    low_time_in.assign(n + 2, 0);
    for (int i = 1 ; i <= m ; ++i) {
        int src, dest; cin >> src >> dest;
        graph[src].push_back(dest);
        graph[dest].push_back(src);
    }
    dfs(1, 0);
    cout << answer.size() << "\n";
    for (auto& connected_component : answer) {
        for (auto node : connected_component) {
            cout << node << " ";
        }
        cout << "\n";
    }
    return 0;
}