#include <iostream>
#include <fstream>
#include <vector>
#include <stack>

using namespace std;

vector<int> disc;
vector<int> low;
stack<pair<int, int>> s;
int comp = 0;
int n;

void dfs(int u,vector<int>* g, vector<int> *res,int p) {
	static int time = 0;
	int children = 0;
	disc[u] = low[u] = ++time;
	for (int v : g[u])
		if (disc[v] == -1) {
			++children;
			s.push({ u,v });
			dfs(v, g, res, u);
			low[u] = min(low[u], low[v]);
			if ((p==-1 && children>=2) || (p != -1 && low[v] >= disc[u])) {
				++comp;
				vector<bool> viz(n + 1, false);
				pair<int, int> e;
				do{
					e = s.top();
					s.pop();
					if (viz[e.first] == false) {
						viz[e.first] = true;
						res[comp].push_back(e.first);
					}
					if (viz[e.second] == false) {
						viz[e.second] = true;
						res[comp].push_back(e.second);
					}
				} while (e.first != u || e.second != v);
			}
		}
		else if (v != p) {
			low[u] = min(low[u], disc[v]);
			if (disc[v] < disc[u])
				s.push({ u,v });
		}

	if (p == -1 && !s.empty()) {
		++comp;
		vector<bool> viz(n + 1, false);
		pair<int, int> e;
		while (!s.empty()) {
			e = s.top();
			s.pop();
			if (viz[e.first] == false) {
				viz[e.first] = true;
				res[comp].push_back(e.first);
			}
			if (viz[e.second] == false) {
				viz[e.second] = true;
				res[comp].push_back(e.second);
			}
		}
	}
}

void biconnectedComponents(vector<int>* g,int n, vector<int> *res) {
	for (int i = 1;i <= n;++i)
		if (disc[i] == -1) {
			dfs(i, g, res, -1);
		}
}

int main()
{
	ifstream fin("biconex.in");
	ofstream fout("biconex.out");

	vector<int> *g;
	int m;

	fin >> n >> m;
	g = new vector<int>[n + 1];
	disc.resize(n + 1, -1);
	low.resize(n + 1);

	while (m--) {
		int x, y;
		fin >> x >> y;
		g[x].push_back(y);
		g[y].push_back(x);
	}

	vector<int> res[100000];
	biconnectedComponents(g, n, res);
	fout << comp << '\n';
	for (int i = 1;i <= comp;++i) {
		for (int u : res[i]) {
			fout << u << ' ';
		}
		fout << '\n';
	}

	return 0;
}