#include<fstream>
#include<vector>
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int N,M,x,y,nr,comp,v1[100001],v2[100001],st[100001];
vector <int> G[100001],sol[100001];
void DFS(int nod){
    st[++nr]=nod;
    for(int i=0;i<(int)G[nod].size();++i)
        if(!v1[G[nod][i]]){
            int k=nr;
            v1[G[nod][i]]=v2[G[nod][i]]=v1[nod]+1;
            DFS(G[nod][i]);
            v2[nod]=min(v2[nod],v2[G[nod][i]]);
            if(v2[G[nod][i]]>=v1[nod]){
                ++comp;
                while(k>nr)sol[comp].push_back(st[k--]);
                sol[comp].push_back(nod);
            }
        }else v2[nod]=min(v2[nod],v1[G[nod][i]]);
}
int main()
{
    f>>N>>M;
    while(M--){
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    v1[1]=v2[1]=1;
    DFS(1);
    g<<comp<<'\n';
    for(int i=1;i<=comp;++i){
        for(int j=0;j<(int)sol[i].size();++j)g<<sol[i][j]<<' ';
        g<<'\n';
    }
    return 0;
}