#include <fstream>
#include <vector>
#include <algorithm>
#include <stack>
#include <algorithm>
#define NMAX 100100
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n,m,viz[NMAX],t[NMAX],low[NMAX],niv[NMAX],critic[NMAX],nr,written[NMAX];
vector<int> G[NMAX];
vector < vector<int> > comp;
stack< pair<int,int> > muchii;
void citire(){
    f>>n>>m;
    int i,x,y;
    for(i=1;i<=m;i++){
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
}
void memComp(int x,int y){
    vector<int> C;
    pair<int,int> MCT,M1=make_pair(x,y),M2=make_pair(y,x);
    do{
        MCT=muchii.top();
        C.push_back(MCT.first);
        C.push_back(MCT.second);
        muchii.pop();
    }while(M1!=MCT&&M2!=MCT);
    comp.push_back(C);
}
void dfs(int x){
    viz[x]=1;
    low[x]=niv[x];
    for(int i=0;i<G[x].size();i++){
        if(viz[G[x][i]]==0){
            muchii.push(make_pair(x,G[x][i]));
            niv[G[x][i]]=niv[x]+1;
            t[G[x][i]]=x;
            if(x==1)
                ++nr;
            dfs(G[x][i]);
            if(low[x]>low[G[x][i]])
                low[x]=low[G[x][i]];
            if(low[G[x][i]]>=niv[x]){
                critic[x]=1;
                memComp(x,G[x][i]);
            }
        }
        else if(G[x][i]!=t[x]&&low[x]>niv[G[x][i]]){
            low[x]=niv[G[x][i]];
            muchii.push(make_pair(x,G[x][i]));
        }
    }
}
int main(){
    citire();
    dfs(1);
    if(nr>1)
        critic[1]=1;
    g<<comp.size()<<'\n';
    for(int i=0;i<comp.size();i++){
        sort(comp[i].begin(),comp[i].end());
        for(int j=0;j<comp[i].size();j++)
            written[comp[i][j]]=i;
        for(int j=0;j<comp[i].size();j++){
            if(written[comp[i][j]]==i){
                g<<comp[i][j]<<' ';
                written[comp[i][j]]=-1;
            }
        }
        g<<'\n';
    }
    return 0;
}