#include<stdio.h>
#include<algorithm>
using namespace std;

struct nod {int inf; nod *urm;} *v[100111], *sol[100111];
int n, m, u, st[400111], low[100111], df[100111], nrsol, viz[100111];

void add(int x, int y){
	nod *p = new nod;
	p->inf = y;
	p->urm = v[x];
	v[x] = p;
}

void citire(){
	
	FILE *f = fopen("biconex.in", "r");
	fscanf(f,"%d %d",&n,&m);
	
	int i, x, y;
	for(i=1; i<=m; i++){
		fscanf(f,"%d %d",&x,&y);
		add(x,y);
		add(y,x);
	}
	
	fclose(f);
}

void update(int x, int y){
	int z1,z2;
	do
	{
		z1=st[u];
		z2=st[u-1];
		
		nod *p=new nod;
		p->inf=z1;
		p->urm=sol[nrsol];
		sol[nrsol]=p;
		
		nod *q=new nod;
		q->inf=z2;
		q->urm=sol[nrsol];
		sol[nrsol]=q;
		u-=2;
	}
	while(z1-y || z2-x);

}


void DFS(int nc, int nr, int ta){

	nod *p;
	low[ nc ] = df[ nc ] = nr;
	
	for(p = v[nc]; p != NULL; p = p->urm){
		
		if( ta != p->inf ){
			if( !viz[p->inf] ){
				viz[p->inf] = 1;
				low[nc] = df[nc];
				st[++u] = nc;
				st[++u] = p->inf;
				DFS(p->inf, nr+1, nc);
				
				if( low[ p->inf ] >=  df[nc]){
					//scoatem din stiva 
					nrsol++;
					update(nc, p->inf);
				}
				low[nc] = min(low[nc], low[p->inf]);
			
			}
			
			else
				low[nc] = min(low[nc], df[p->inf]);
			
		}
	}
}


void solve(){

	int i;
	for(i=1; i<=n; i++)
		if(!viz[i]){
			viz[i] = 1;
			DFS(i,1,0);
		}
}


void afisare(){
	int i;
	nod *p;
	FILE *g = fopen("biconex.out", "w");
	fprintf(g,"%d\n",nrsol);
	
	for(i=1; i<=nrsol; i++){
		for(p = sol[i]; p != NULL; p = p->urm)
			viz[p->inf] = 0;
		
		for(p = sol[i]; p != NULL; p = p->urm)
			if(!viz[p->inf]){
				fprintf(g,"%d ",p->inf);
				viz[p->inf] = 1;
			}
			
		fprintf(g,"\n");
	}
	
	fclose(g);
}

int main(){

	citire();
	solve();
	afisare();
	
	return 0;
}