#include <bits/stdc++.h>

using namespace std;

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

private:
    class Edge {
    public:
        int x, y;
        Edge() { }
        Edge(int x, int y) : x(x), y(y) { }
        bool operator!=(const Edge& other) { return x != other.x || y != other.y; }
    };

    static const int NMAX = (int)1e5 + 5;

    int n, m, source, timestamp = 0;
    vector<int> adj[NMAX];

    vector<int> parent;
    vector<int> found;
    vector<int> low_link;
    stack<Edge> edges_stack;

    void read_input() {
        ifstream fin("biconex.in");
        fin >> n >> m;
        for (int i = 1, x, y; i <= m; i++) {
            fin >> x >> y;
            adj[x].push_back(y);
            adj[y].push_back(x);
        }
        fin.close();
    }

    // TARJAN
    vector<vector<int>> ctc_tarjan() {
        vector<vector<int>> cbc;
        parent.resize(n + 1, -1);
        found.resize(n + 1, 0);
        low_link.resize(n + 1, 0);

        for (int node = 1; node <= n; ++node) {
            if (parent[node] == -1) {
                parent[node] = node;
                dfs(node, cbc);
            }
        }

        return cbc;
    }

    void dfs(int node, vector<vector<int>> &cbc) {
        found[node] = ++timestamp;
        low_link[node] = timestamp;

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

                edges_stack.push(Edge(node, neighbor));

                dfs(neighbor, cbc);
                low_link[node] = min(low_link[node], low_link[neighbor]);

                if (low_link[neighbor] >= found[node]) {
                    unordered_set<int> scc;
                    Edge edge;
                    do {
                        edge = edges_stack.top();
                        edges_stack.pop();
                        scc.insert(edge.x);
                        scc.insert(edge.y);
                    } while (edge != Edge(node, neighbor));
                    cbc.push_back(vector<int>{scc.begin(), scc.end()});
                }

            } else if (parent[node] != neighbor) {
                low_link[node] = min(low_link[node], found[neighbor]);
            }
        }
    }

    void print_output(const vector<vector<int>> &cbc) {
        ofstream fout("biconex.out");
        fout << cbc.size() << '\n';
        for (const auto &scc : cbc) {
            for (auto node : scc) {
                fout << node << ' ';
            }
            fout << '\n';
        }
        fout.close();
    }
};

int main() {
    auto* task = new (nothrow) Task();
    if (!task) {
        cerr << "Error\n";
        return -1;
    }
    task->solve();
    delete task;
    return 0;
}