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

using VI = vector<int>;
using VVI = vector<VI>;
using PI = pair<int, int>;

int n, m, nivel;
VI c, t, niv, L;
VVI G, comp;
stack<PI> stk;

void Read();
void Tarjan(int x);
void Write();

int main()
{
	Read();
	Tarjan(1);
	Write();
}

void Write()
{
	ofstream fout("biconex.out");
	fout << comp.size() << '\n';
	for (VI& c : comp)
	{
		sort(c.begin(), c.end());
		c.erase(unique(c.begin(), c.end()), c.end());
		for (const int& x : c)
			fout << x << ' ';
		fout << '\n';
	}
	fout.close();
}

void Tarjan(int x)
{
	niv[x] = L[x] = ++nivel;
	int x1, x2;
	for (const int& y : G[x])
	{
		if (y == t[x])	
			continue;
		if (!niv[y])
		{
			stk.push({x, y});
			t[y] = x;
			Tarjan(y);
			L[x] = min(L[x], L[y]);
			if (L[y] >= niv[x])
			{
				c.clear();
				while (true)
				{
					x1 = stk.top().first;
					x2 = stk.top().second;
					stk.pop();
					c.push_back(x1);
					c.push_back(x2);
					if (x1 == x && x2 == y)
						break;
				}
				comp.push_back(c);
			}
		}
		else
			L[x] = min(L[x], niv[y]);
	}
}

void Read()
{
	ifstream fin("biconex.in");
	fin >> n >> m;
	G = VVI(n + 1);
	niv = L = t = VI(n + 1);
	int x, y;
	for (int i = 0; i < m; i++)
	{
		fin >> x >> y;
		G[x].push_back(y);
		G[y].push_back(x);
	}
	fin.close();
}