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