#include<bits/stdc++.h>

#define MAXN 200005

int n,m,x,y;
std::vector<int> g[MAXN];
int dfn[MAXN],low[MAXN],idx;
int st[MAXN],tp;
std::vector<std::vector<int>> ans;

void tarjan(int u,int fa){
//	std::cout<<"TARJAN"<<' '<<u<<' '<<fa<<'\n';
	dfn[u]=low[u]=++idx;
	st[++tp]=u;
	for(int v:g[u]){
		if(v==fa) continue;
		if(!dfn[v]){
			tarjan(v,u);
			low[u]=std::min(low[u],low[v]);
		}else low[u]=std::min(low[u],dfn[v]);
	}
	if(low[u]==dfn[u]){
		std::vector<int> now;
		while(st[tp]!=u){
			now.push_back(st[tp--]); 
		}
		now.push_back(st[tp--]);
		ans.push_back(now);
	}
	
	return;
}

int main(){
	std::ios::sync_with_stdio(false);
	
	std::cin>>n>>m;
	for(int i=1;i<=m;i++){
		std::cin>>x>>y;
		g[x].push_back(y),g[y].push_back(x);
	}
	for(int i=0;i<=n-1;i++){
		if(!dfn[i]) tarjan(i,0);
	}
	std::cout<<ans.size()<<'\n';
	for(std::vector<int> nvec:ans){
		std::cout<<nvec.size()<<' ';
		for(int j:nvec) std::cout<<j<<' ';
		std::cout<<'\n'; 
	}
	
	return 0;
}