#include<fstream>
#include<vector>
#include<algorithm>
#include<stack>
#define DN 100005
#define pb push_back
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
int n,m,niv[DN],low[DN],p,q,nr,f;
stack<int>s;
vector<int>r[DN];
vector<int>v[DN];
void dfs(int nod)
{
	low[nod]=niv[nod];
	s.push(nod);
	for(auto i:v[nod])
	{
		if(niv[i])
			low[nod]=min(low[nod],niv[i]);
		else
		{
			niv[i]=niv[nod]+1;
			dfs(i);
			low[nod]=min(low[nod],low[i]);
			if(low[i]>=niv[nod])
			{
				nr++;
				r[nr].pb(nod);
				while(1)
				{
					f=s.top();
					r[nr].pb(f);
					s.pop();
					if(f==i)
						break;
				}
			}
		}
	}
}
int main()
{
	fin>>n>>m;
	for(int i=1;i<=m;i++)
	{
		fin>>p>>q;
		v[p].pb(q);
		v[q].pb(p);
	}
	for(int i=1;i<=n;i++)
		if(niv[i]==0)
		{
			niv[i]=1;
			dfs(i);
		}
	for(int i=1;i<=nr;i++)
		sort(r[i].begin(),r[i].end());
	fout<<nr<<'\n';
	for(int i=1;i<=nr;i++)
	{
		for(auto j:r[i])
			fout<<j<<' ';
		fout<<'\n';
	}
}