#include <fstream>
#include <vector>
using namespace std;
ifstream f ("biconex.in");
ofstream g ("biconex.out");
const int nmax=1e5+3;
int n,m,comp,k,x,y,t2[nmax],st[nmax],t1[nmax];
vector <int> v[nmax];
vector <int> sol[nmax];
void dfs(int nod)
{
    st[++k]=nod;
    for(int i=0;i<v[nod].size();++i)
    {
        if(!t1[v[nod][i]])
        {
            int ck=k;
            t1[v[nod][i]]=t2[v[nod][i]]=t1[nod]+1;
            dfs(v[nod][i]);
            t2[nod]=min(t2[nod],t2[v[nod][i]]);
            if(t2[v[nod][i]]>=t1[nod])
            {
                ++comp;
                while(k>ck) sol[comp].push_back(st[k--]);
                sol[comp].push_back(nod);
            }
        }
        else t2[nod]=min(t2[nod],t1[v[nod][i]]);
    }
}
int main()
{
    f>>n>>m;
    while(m--)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    t1[1]=t2[1]=1;
    dfs(1);
    g<<comp<<'\n';
    for(int i=1;i<=comp;++i)
    {
        for(int j=0;j<sol[i].size();++j) g<<sol[i][j]<<' ';
        g<<'\n';
    }
    return 0;
}