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

const int kNmax = 100005;

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

private:
	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<int> stiva;

	void read_input() {
		cin >> n >> m;
		for (int i = 1, x, y; i <= m; i++) {
			cin >> x >> y;
			adj[x].push_back(y);
			adj[y].push_back(x);
		}
	}

	void DFS(vector<vector<int>> &componente, 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;
					DFS(componente, *it);
					if (lowLink[nod] > lowLink[*it]) {
						lowLink[nod] = lowLink[*it];
					}
				}
				else { // intotdeauna gri ptr grafuri neorientate
					if (lowLink[nod] > idx[*it])
						lowLink[nod] = idx[*it];
				}
			}
		}

		if (idx[nod] == lowLink[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);
		}
	}

	vector<vector<int>> 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);
		}
		vector<vector<int>> componente;
		for (int i = 1; i <= n; ++i) {
			//if (!color[i]) {
			timp = 0;
			if (!idx[i]) {
				DFS(componente, i);
			}
		}
		/*
		TODO: Gasiti muchiile critice ale grafului neorientat stocat cu liste
		de adiacenta in adj.
		*/
		return componente;
	}

	void print_output(vector<vector<int>> result) {
		cout << result.size() << '\n';
		for (const auto& ctc : result) {
			for (int nod : ctc) {
				cout << nod << ' ';
			}
			cout << '\n';
		}
	}
};

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