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

int n, m,nrComp;
int k,i, j,depth[100005],low[100005],parent[100005];
vector<vector<int>> graph;
vector<vector<int>> graphComp;
stack<pair<int,int>> st;
vector<bool> visited;

void makeBiconexComp(int vertex,int node)
{
	int kv, kn;
	do
	{
		kv = st.top().first;
		kn = st.top().second;
		graphComp[nrComp].push_back(st.top().second);
		st.pop();
	} while (kv != vertex && kn != node);
	graphComp[nrComp].push_back(vertex);
	++nrComp;
}

void dfsBiconex(int vertex,int deep)
{
	depth[vertex] = low[vertex] = deep;
	visited[vertex] = true;
	for (auto node:graph[vertex])
	{
		
		if (!visited[node])
		{
			st.push({ vertex,node });
			parent[node] = vertex;
			dfsBiconex(node, ++deep);
			if (low[node] >= depth[vertex])
				makeBiconexComp(vertex,node);
			low[vertex] = low[vertex] < low[node] ? low[vertex] : low[node];
			
		}
		else if (node != parent[vertex])
		{
			low[vertex] = low[vertex] < low[node] ? low[vertex] : low[node];
		}
	}
}

int main()
{
	ifstream fin("biconex.in");
	ofstream fout("biconex.out");
	fin >> n >> m;
	graph.resize(n);
	graphComp.resize(n);
	visited.resize(n, false);
	int x, y;
	for (int i = 0;i < m;++i)
	{
		fin >> x >> y;
		--x;
		--y;
		graph[x].push_back(y);
		graph[y].push_back(x);
	}
	dfsBiconex(0,1);
	fout << nrComp << "\n";
	for (i = 0;i < nrComp;++i)
	{
		for (auto j : graphComp[i])
			fout << j+1 << " ";
		fout << "\n";
	}
	fin.close();
	fout.close();
	return 0;
}