#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ull unsigned long long
#define i128 __int128
#define pii pair<int,int>
#define fir first
#define sec second
#define chmin(a,b) a=min(a,b)
#define chmax(a,b) a=max(a,b)
#define pb push_back
const int inf=0x3f3f3f3f3f3f3f3f;
const int mod=998244353;
int n,m,dfn[3000010],low[3000010],dfc,fa[3000010],val[3000010],cnt,pm;
bool b[3000010],vis[3000010],b2[3000010];
int ui[3000010],vi[3000010];
ull w[3000010];
unordered_map<ull,int>mp,ed;
mt19937_64 rnd(time(0));
inline int randint(){return rnd();}//|1ull*rnd()<<64;}
vector<pii>g[3000010];
vector<int>ans[3000010];
void tarjan(int u,int f)
{
	dfn[u]=low[u]=++dfc;
	for(auto x:g[u])
	{
		int v=x.fir,id=x.sec;
		if(!dfn[v])
		{
			tarjan(v,/*u*/id);
			chmin(low[u],low[v]);
//			if(low[v]>dfn[u])b[id]=b[id^1]=1;
			if(low[v]>=dfn[v])b[id]=b[id^1]=1;
		}
		else if(/*v!=f*/id!=(f^1))chmin(low[u],dfn[v]);
	}
}
void dfs3(int u,int f)
{
//	cout<<" dfs3:   "<<u<<endl;
	ans[cnt].pb(u);
	for(auto x:g[u])
	{
		int v=x.fir;
		int id=x.sec;
//		cout<<"!!!!!!!!!!!!"<<u<<" "<<v<<endl;
//		if(!b[v]&&!b2[v]&&vis[v]&&v!=f)
		if(!b[id]&&!b2[id]&&vis[id]&&v!=f)
			dfs3(v,f);
	}
}
void dfs2(int u,int eid)
{
//	cout<<" dfs2:"<<u<<endl;
	for(auto x:g[u])
	{
		int v=x.fir,id=x.sec;
		if(!b[id]&&!b2[id]&&vis[id])dfs2(v,id);
	}
	if(mp[w[u]])
//	if(mp[w[u]]!=mp.find)
	{
		int v=mp[w[u]];
//		cout<<"difnew:   "<<u<<" "<<v<<endl;
		cnt++;
		dfs3(u,v);
		vis[eid]=0;
		int f=fa[u];
		g[f].pb({v,++pm});
		vis[pm]=1;
		fa[v]=f;
		mp[w[u]]=v; 
	}
	else mp[w[u]]=u;
}
void dfs(int u,int fr,int eid)
{
	dfn[u]=++dfc;
//	cout<<"dfn["<<u<<"]="<<dfn[u]<<endl;
	for(auto x:g[u])
	{
		int v=x.fir,id=x.sec;
//		if(!b[v]&&v!=f)
//		if(!b[id]&&v!=f)
		if(!b[id]&&id!=(eid^1))
		{
			
			if(dfn[v])
			{
				if(dfn[v]>dfn[u])continue;
//				val[id]=randint();
				ull vi=randint();
//				cout<<"!!val="<<val[id]<<endl;
				w[u]^=vi;
				w[v]^=vi;
				ed[vi]=1;
			}
			else
			{
				
//				cout<<" dvdv "<<u<<" "<<v<<endl;
				vis[id]=1;
				fa[v]=u;
				dfs(v,id/*,u*/,id);
				w[u]^=w[v];
			}
		}
	}
//	cout<<"!!!  dfs1:"<<u<<endl;
	if(ed[w[u]])b2[eid]=b2[eid^1]=1;//,cout<<"dsfavfb"<<eid<<endl;
	if(b2[eid]||!eid)
	{
//		cout<<" !!!"<<u<<" "<<eid<<endl;
		mp.clear();
		dfs2(u,0);
//		vis[eid]=0;
		cnt++;
		dfs3(u,0);
	}
}
bool cmp(vector<int>a,vector<int>b)
{
	return a[0]<b[0];
}
signed main()
{
	cin>>n>>m;
	for(int i=1;i<=m;i++)
	{
//		int u,v;
		cin>>ui[i]>>vi[i];
		ui[i]++,vi[i]++;
//		cout<<"gfhnsb  "<<i<<" "<<ui[i]<<" "<<vi[i]<<endl; 
//		g[u].pb(v);
		g[ui[i]].pb({vi[i],2*i});
		g[vi[i]].pb({ui[i],2*i+1});
//		val[i]=randint();
	} 
	for(int i=1;i<=n;i++)
		if(!dfn[i])
			tarjan(i,0);
//	cout<<"tarjan:end"<<endl;
//	for(int i=1;i<=m;i++)cout<<b[i];
//	cout<<endl;
	memset(dfn,0,sizeof(dfn));
	dfc=0;
	pm=2*m+1;
	for(int i=1;i<=n;i++)
		if(!dfn[i])
			dfs(i,0,0);
			
			
	for(int i=1;i<=cnt;i++)sort(ans[i].begin(),ans[i].end());
	sort(ans+1,ans+cnt+1/*,cmp*/);
	cout<<cnt<<endl;
	for(int i=1;i<=cnt;i++)
	{
		cout<<ans[i].size()<<" ";
		for(auto x:ans[i])cout<<x-1<<" ";
		cout<<endl;
	}
	return 0;
}
/*
5 7
1 2
1 3
1 4
2 3
2 4
3 4
5 5
*/