#include<bits/stdc++.h>
#define ffor(i,a,b) for(int i=(a);i<=(b);i++)
#define roff(i,a,b) for(int i=(a);i>=(b);i--)
using namespace std;
const int MAXN=2e5+10;
int n,m,low[MAXN],dfn[MAXN],tot;
stack<int> st;
vector<vector<int>> ans;
vector<int> G[MAXN];
void dfs(int u,int f) {
	int cnt=0;
	dfn[u]=low[u]=++tot,st.push(u);;
	for(auto v:G[u]) {
		if(!cnt&&v==f) {cnt=1;continue ;}
		if(dfn[v]) low[u]=min(low[u],dfn[v]);
		else dfs(v,u),low[u]=min(low[u],low[v]);	
	}
	if(low[u]==dfn[u]) {
		vector<int> nw;
		while(st.top()!=u) nw.push_back(st.top()),st.pop();
		nw.push_back(u),st.pop(),ans.push_back(nw);
	}
	return ;
}
int main() {
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	cin>>n>>m;
	ffor(i,1,m) {
		int u,v;
		cin>>u>>v,u++,v++;
		if(u==v) continue ;
		G[u].push_back(v),G[v].push_back(u);	
	}
	ffor(i,1,n) if(!dfn[i]) dfs(i,0);
	cout<<ans.size()<<'\n';
	for(auto vc:ans) {
		cout<<vc.size()<<' ';
		for(auto u:vc) cout<<u-1<<' ';
		cout<<'\n';	
	}
	return 0;
}