#include<fstream>
#include<cmath>
#include<iostream>
#define DN 100005
#include<vector>
#include<cctype>
#include<cstring>
#include<stack>
#define pb push_back
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
int n,low[DN],niv[DN],f,g,m,rez,nr;
vector<int>v[DN];
vector<int>r[DN];
stack<int>s;
void dfs(int nod,int f)
{
    low[nod]=niv[nod];
    s.push(nod);
    for(auto i:v[nod])
        if(i!=f)
        {
            if(niv[i]>0)
                low[nod]=min(low[nod],niv[i]);
            else
                {
                    niv[i]=niv[nod]+1;
                    dfs(i,nod);
                    low[nod]=min(low[nod],low[i]);
                    if(low[i]>=niv[nod])
                    {
                        rez++;
                        r[rez].pb(nod);
                        while(1)
                        {
                            r[rez].pb(s.top());
                            if(s.top()==i)
                            {
                                s.pop();
                                break;
                            }
                            s.pop();
                        }
                    }
                }
        }
}
int main()
{
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        fin>>f>>g;
        v[f].pb(g);
        v[g].pb(f);
    }
    for(int i=1;i<=n;i++)
        if(niv[i]==0)
        {
            niv[i]=1;
            dfs(i,0);
        }
    fout<<rez<<'\n';
    for(int i=1;i<=rez;i++)
    {
        for(auto j:r[i])
            fout<<j<<' ';
        fout<<'\n';
    }
}