#include <fstream>
#include <iostream>
#include <vector>
#include <algorithm>
#include <stack>
#include <set>
using namespace std;

const int kNmax = 100005;

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

private:

	struct Edge {
		int x;
		int y;
	};

	int n;
	int m;
	vector<int> adj[kNmax];
	//vector<int> color;
	//vector<int> critic;
	vector<int> parent;
	vector<int> idx;
	vector<int> lowLink;
	int timp;
	stack<Edge> stiva;
	set<int> _set;
	vector<set<int>> componente;

	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);
		}
	}

	void DFS(int nod) {
		//color[nod] = 1;
		idx[nod] = lowLink[nod] = ++timp;
		vector<int>::iterator it;
		//stiva.push(nod);
		//int childCounter = 0;
		for (it = adj[nod].begin(); it != adj[nod].end(); ++it) {
			if (*it != parent[nod]) {
				//if (!color[*it]) {
				if (!idx[*it]) {
					//childCounter++;
					parent[*it] = nod;
					stiva.push({ nod, *it });
					DFS(*it);
					if (lowLink[nod] > lowLink[*it]) {
						lowLink[nod] = lowLink[*it];
					}
					if (idx[nod] <= lowLink[*it]) {
						int x, y;
						componente.push_back(_set);
						set<int> &v = componente[componente.size()-1];
						do {
							x = stiva.top().x;
							y = stiva.top().y;
							stiva.pop();
							v.insert(x);
							v.insert(y)	;
						} while (x != nod && y != nod);
						// muchie critica - deci capetele formeaza o componenta biconexa
					}
				}
				else { // intotdeauna gri ptr grafuri neorientate
					if (lowLink[nod] > idx[*it])
						lowLink[nod] = idx[*it];
				}
			}
		}
		/*
		if (idx[nod] == lowLink[nod]) {
			if (stiva.top() != nod) {
				vector<int> v;
				int x;
				do {
					x = stiva.top();
					v.push_back(x);
					//color[x] = 2;
					stiva.pop();
				} while (x != nod);
				componente.push_back(v);
			} // un element nu formeaza o componenta
		}*/
	}

	void get_result() {
		for (int i = 0; i <= n; ++i) {
			//color.push_back(0);
			//critic.push_back(0);
			parent.push_back(0);
			idx.push_back(0);
			lowLink.push_back(0);
		}
		for (int i = 1; i <= n; ++i) {
			//if (!color[i]) {
			timp = 0;
			if (!idx[i]) {
				DFS(i);
			}
		}
		/*
		TODO: Gasiti muchiile critice ale grafului neorientat stocat cu liste
		de adiacenta in adj.
		*/
	}

	void print_output() {
		ofstream fout("biconex.out");
		fout << componente.size() << '\n';
		for (const auto& ctc : componente) {
			for (int nod : ctc) {
				fout << nod << ' ';
			}
			fout << '\n';
		}
		fout.close();
	}
};

int main() {
	Task *task = new Task();
	task->solve();
	delete task;
	return 0;
}