#include<bits/stdc++.h>
#define pb push_back
using namespace std;
const int N=100020;
vector <int> lda[N], rs[N];
int p[N], t[N], s[N], r, st;
int dfs(int nod){
	s[++st]=nod;
	int m=lda[nod].size();
	for(int i=0;i<m;i++){
		int y=lda[nod][i];
		if(p[y])p[nod]=min(p[nod], t[y]);else{
			int x=st;
			t[y]=p[y]=t[nod]+1;
			dfs(y);
			p[nod]=min(p[y], p[nod]);
			if(p[y]>=t[nod]){
				rs[++r].pb(nod);
				while(st>x)rs[r].pb(s[st--]);
			}
		}
	}
}
int main(){
	ifstream f("biconex.in");
	ofstream g("biconex.out");
	int n,m,x,y;
	f>>n>>m;
	while(m--){
		f>>x>>y;
		lda[x].pb(y);
		lda[y].pb(x);
	}
	t[1]=p[1]=1;
	dfs(1);
	g<<r<<'\n';
	for(int i=1;i<=r;i++, g<<'\n')for(int j=0;j<rs[i].size(); j++)g<<rs[i][j]<<' ';
}