#include<fstream>
#include<vector>
#include<stack>
#define pb push_back
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
const int DN=1e5+5;
int n,m,niv[DN];
int f,g,low[DN],cnt;
vector<int>v[DN],r[DN];
stack<int>stk;
void dfs(int nod)
{
	stk.push(nod);
	low[nod]=niv[nod];
	for(auto i:v[nod])
	{
		if(niv[i])
		{
			low[nod]=min(low[nod],niv[i]);
			continue;
		}
		niv[i]=niv[nod]+1;
		dfs(i);
		low[nod]=min(low[nod],low[i]);
		if(low[i]>=niv[nod])
		{
			cnt++;
			r[cnt].pb(nod);
			do
			{
				f=stk.top();
				stk.pop();
				r[cnt].pb(f);
			}while(f!=i);
		}
	}
}
int main()
{
	fin>>n>>m;
	while(m--)
	{
		fin>>f>>g;
		v[f].pb(g);
		v[g].pb(f);
	}
	for(int i=1;i<=n;i++)
		if(!niv[i])
		{
			niv[i]=1;
			dfs(i);
		}
	fout<<cnt<<'\n';
	for(int i=1;i<=cnt;i++)
	{
		for(auto j:r[i])
			fout<<j<<' ';
		fout<<'\n';
	}
}