#include <bits/stdc++.h>

#define NMAX 100010
#define edge pair<int, int>

using namespace std;

class Task {
public:
  void solve() {
    read_input();
    get_result();
    print_output();
  }

private:
  int n, m;

  vector<int> adj[NMAX];

  vector<vector<int>> bcc;

  stack<edge> sc;

  vector<int> found;

  vector<int> low_link;

  vector<int> cut_vertex;

  vector<edge> critical_edges;

  vector<int> parent;

  void read_input() {
    cin >> n >> m;
    found = vector<int>(n + 1, -1);
    low_link = vector<int>(n + 1, 0);
    parent = vector<int>(n + 1, 0);
    for (int i = 1; i <= m; ++i) {
      int x, y;
      cin >> x >> y;

      adj[x].push_back(y);
      adj[y].push_back(x);
    }
  }

  void get_result() { tarjan(); }

  void tarjan() {
    int current_start = 0;

    for (int i = 1; i <= n; ++i) {
      if (found[i] ==
          -1) {
        parent[i] = 0;

        dfs(i, current_start);
      }
    }
  }

  void dfs(int node, int &current_start) {
    ++current_start;

    found[node] = current_start;
    low_link[node] = current_start;

    int children = 0;

    for (auto &vecin : adj[node]) {
      if (found[vecin] == -1) {
        parent[vecin] = node;

        ++children;

        sc.push(edge(node, vecin));

        dfs(vecin, current_start);

        low_link[node] = std::min(low_link[node], low_link[vecin]);

        if (low_link[vecin] >= found[node]) {
          if (parent[node] != 0) {
            cut_vertex.push_back(node);
          }

          get_bcc(edge(node, vecin));
        }

        if (low_link[vecin] > found[node]) {
          critical_edges.push_back(edge(node, vecin));
        }
      } else {
        if (vecin != parent[node]) {
          low_link[node] = std::min(low_link[node], found[vecin]);
        }
      }
    }

    if (parent[node] == 0 && children >= 2) {
      cut_vertex.push_back((node));
    }
  }

  void get_bcc(edge target_edge) {
    // folosesc set pt a identifica noduri unice
    set<int> current_bcc;
    vector<int> vecbcc;

    edge current_edge = edge(-1, -1);

    while (current_edge != target_edge) {
      current_edge = sc.top();
      sc.pop();

      current_bcc.insert(current_edge.first);
      current_bcc.insert(current_edge.second);
    }

    // sort(current_bcc.begin(), current_bcc.end());
    // auto it = unique(current_bcc.begin(), current_bcc.end());
    // current_bcc.erase(it, current_bcc.end());

    for (auto it : current_bcc) {
         vecbcc.push_back(it);
    }
    bcc.push_back(vecbcc);
  }

  void print_output() {
    // if (cut_vertex.empty()) {
    //   cout << "Graful nu contine puncte de articulatie\n";
    // } else {
    //   cout << "Punctele de articulatie ale grafului sunt:\n";
    //   for (auto &node : cut_vertex) {
    //     cout << node << ' ';
    //   }
    //   cout << '\n';
    // }
    //
    // if (critical_edges.empty()) {
    //   cout << "Graful nu contine muchii critice\n";
    // } else {
    //   cout << "Muhciile critice ale grafului sunt:\n";
    //   for (auto &E : critical_edges) {
    //     cout << '(' << E.first << ", " << E.second << ") ";
    //   }
    //   cout << '\n';
    // }

    int sol = bcc.size();
    // cout << "Graful are " << sol << " componente biconexe\n";

    ofstream g("biconex.out");
    g << sol << "\n";
    for (int i = 0; i < sol; ++i) {
      // cout << "Componenta biconexa [" << i + 1 << "]: ";
      for (auto &node : bcc[i]) {
        g << node << " ";
      }
      g << '\n';
    }
  }
};

int main() {
  auto cin_buff = cin.rdbuf();
  auto cout_buff = cout.rdbuf();

  ifstream fin("biconex.in");
  cin.rdbuf(fin.rdbuf()); // save and redirect

  Task *task = new Task();
  task->solve();
  delete task;

  cin.rdbuf(cin_buff);
  cout.rdbuf(cout_buff);

  return 0;
}