#include <bits/stdc++.h>
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> idx;
	vector<int> low;
	vector<int> parent;
	int time = 0;

	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();
	}

	void dump(int v, stack<int> &s, vector<int> &bcc) {
		int u;
		do {
			u = s.top();
			s.pop();
			bcc.push_back(u);
		} while (u != v);
	}

	void dfsBCC(int v, stack<int> &s, vector<vector<int>> &bccs) {
		time++;
		idx[v] = time;
		low[v] = time;
		s.push(v);
		int nkids = 0;
		bool cv = false;

		for (int u : adj[v]) 
			if (!idx[u]) {
				nkids++;
				if (nkids > 1 && !parent[v]) {
					vector<int> bcc;
					dump(v, s, bcc);
					bccs.push_back(bcc);
					s.push(v);
				}
				parent[u] = v;
				dfsBCC(u, s, bccs);
				low[v] = min(low[v], low[u]);
				if (low[u] >= idx[v] && parent[v]) {
					vector<int> bcc;
					bcc.push_back(v);
					dump(u, s, bcc);
					bccs.push_back(bcc);
				}
			}
			else if (u != parent[v])
				low[v] = min(low[v], idx[u]);

		if (!parent[v]) {
			vector<int> bcc;
			dump(v, s, bcc);
			bccs.push_back(bcc);
		}
	}

	vector<vector<int>> get_result() {
		/*
		TODO: Gasiti nodurile critice ale grafului neorientat stocat cu liste
		de adiacenta in adj.
		*/
		vector<vector<int>> sol;
		stack<int> s;
		idx.resize(n + 1, 0);
		low.resize(n + 1);
		parent.resize(n + 1, 0);

		for (int i = 1; i <= n; i++)
			if (!idx[i])
				dfsBCC(i, s, sol);
	
		return sol;
	}

	void print_output(vector<vector<int>> result) {
		ofstream fout("biconex.out");
		fout << result.size() << '\n';
		for (int i = 0; i < int(result.size()); i++) {
			for (int j = 0; j < int(result[i].size()); j++)
				fout << result[i][j] << ' ';
			fout << '\n';
		}
		fout.close();
	}
};

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