#include <fstream>
#include <vector>

using namespace std;

ifstream fin("biconex.in");
ofstream fout("biconex.out");

struct sintnode{
    int x;
    sintnode *sp=nullptr;
};

struct sint{
    sintnode *e=nullptr;

    void push(int x);
    void pop();
    int top();
    bool empty();
};

void sint::push(int x){
    sintnode *aux;
    aux=new sintnode;
    aux->sp=e;
    aux->x=x;
    e=aux;
}

void sint::pop(){
    sintnode *p=e;
    e=e->sp;
    delete p;
}

int sint::top(){
    return e->x;
}

bool sint::empty(){
    return e==nullptr;
}

const int nmax=100000;

int low[nmax+1], lvl[nmax+1], l;

bool u[nmax+1];

vector <int> g[nmax+1];

sint s;

vector < vector <int> > sol;

void dfs(int x){
    l++;
    lvl[x]=l;
    low[x]=l;
    u[x]=1;
    s.push(x);
    for(int i=0;i<int(g[x].size());i++){
        int xn=g[x][i];
        if(lvl[xn]==0){
            dfs(xn);
            if(low[x]>low[xn]){
                low[x]=low[xn];
            }
            if(low[xn]==lvl[x]){
                int nsol=sol.size()+1;
                sol.resize(nsol);
                sol[nsol-1].resize(0);
                while(u[xn]==1){
                    int aux=s.top();
                    s.pop();
                    u[aux]=0;
                    sol[nsol-1].push_back(aux);
                }
                sol[nsol-1].push_back(x);
            }
        }else if(u[xn]==1){
            if(low[x]>lvl[xn]){
                low[x]=lvl[xn];
            }
        }
    }
}

int main(){
    int n,m;
    fin>>n>>m;
    for(int i=1;i<=m;i++){
        int x,y;
        fin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    for(int i=1;i<=n;i++){
        if(lvl[i]==0){
            dfs(i);
            s.pop();
        }
    }
    fout<<sol.size()<<"\n";
    for(int i=0;i<int(sol.size());i++){
        for(int j=0;j<int(sol[i].size());j++){
            fout<<sol[i][j]<<" ";
        }
        fout<<"\n";
    }
    return 0;
}