#include <iostream>
#include <fstream>
#include <stack>
#include <vector>
#define DIM 100010
using namespace std;
ifstream fin ("biconex.in");
ofstream fout("biconex.out");
int v[DIM],NIV[DIM],LOW[DIM];
int componente,n,m,x,y,p,i,j,k,tp;
stack <int> ST;
vector<int> L[DIM],C[DIM];
void dfs(int nod,int tata,int niv){
    v[nod]=1;
    NIV[nod]=niv;
    LOW[nod]=niv;
    ST.push(nod);
    for(int i=0;i<L[nod].size();i++){
        int vecin = L[nod][i];
        if(vecin==tata)
            continue;
    if(v[vecin])
        LOW[nod]=min(LOW[nod],NIV[vecin]);
    else{
        dfs(vecin,nod,niv+1);
        LOW[nod]=min(LOW[nod],LOW[vecin]);
        if(LOW[vecin] >= NIV[nod]){
            componente++;
            do{
                tp = ST.top();
                C[componente].push_back(tp);
                ST.pop();
            }while(tp != vecin);
            C[componente].push_back(nod);
        }
    }
    }
}
int main(){
    fin>>n>>m;
    for(i=1;i<=m;i++){
        fin>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    dfs(1,0,1);
    fout<<componente<<"\n";
    for(i=1;i<=componente;i++){
        for(j=0;j<C[i].size();j++)
        fout<<C[i][j]<<" ";
        fout<<"\n";
    }
    return 0;
}