#include<fstream>
#include<algorithm>
#include<vector>
using namespace std;
ifstream in("biconex.in");
ofstream out("biconex.out");
const int Nmax = 100001;
vector<int> G[Nmax],C[Nmax];
int N,M,L[Nmax],S[Nmax],K;
int dfs(int x,int l){
    S[++S[0]]=x;
    L[x]=l;
    int h=l;
    for(vector<int>::iterator it=G[x].begin();it!=G[x].end();it++){
        if(!L[*it]){
            int st=S[0];
            int r=dfs(*it,l+1);
            if(r>=L[x]){
                K++;
                while(S[0]>st) C[K].push_back(S[S[0]--]);
                C[K].push_back(x);
            }
            h=min(h,r);
        }
        else if(L[*it]!=l-1) h=min(h,L[*it]);
    }
    return h;
}
int main(){
    in>>N>>M;
    int x,y;
    for(int i=1;i<=M;i++){
        in>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    dfs(1,1);
    out<<K<<'\n';
    for(int i=1;i<=K;i++){
        for(vector<int>::iterator it=C[i].begin();it!=C[i].end();++it) out<<*it<<' '; out<<'\n';
    }
    return 0;
}