#include <iostream>
#include <bits/stdc++.h>
#define INFILE "biconex.in"
#define OUTFILE "biconex.out"
using namespace std;
typedef pair<int,int> edge;
ifstream in(INFILE);
ofstream out(OUTFILE);
int N,M;
vector<vector<int>> ComponenteBiconexe;
map<int,int> dnum;
map<int,int> low;
map<int,bool> viz;
map<int,bool> artPoint;
stack<edge> S;

void AddToCompBiconexe(edge e){
    vector<int> v;
    while(!S.empty()&&S.top()!=e){
        edge s=S.top();
        v.push_back(s.second);
        S.pop();
    }
    if(!S.empty()){
        edge s=S.top();
        v.push_back(s.second);
        v.push_back(s.first);
        S.pop();
    }
    reverse(v.begin(),v.end());
    ComponenteBiconexe.push_back(v);
}

struct Graph{
    int n;
    vector<vector<int>> Adj;
    void Init(int sz){
        n=sz;
        Adj.resize(n+1);
    }
    void Add(int x,int y){
        Adj[x].push_back(y);
        Adj[y].push_back(x);
    }
}G;

void Read(){
    in>>N>>M;
    G.Init(N);
    for(int i=1;i<=M;i++){
        int x,y;
        in>>x>>y;
       // cout<<x<<" "<<y<<endl;
        G.Add(x,y);
    }
}
int nrfii=0;
void DFS(int x,int tx){
    viz[x]=true;
    dnum[x]=dnum[tx]+1;
    low[x]=dnum[x];
    for(auto y:G.Adj[x]){
        if(viz[y]&&y==0) nrfii++;
        if(!viz[y]){
            S.push(make_pair(x,y));
            DFS(y,x);
            low[x]=min(low[x],low[y]);
            if(low[y]>=dnum[x])
                artPoint[x]=true;
            if(tx==0&&nrfii>=2)
                artPoint[x]=true;
            if(artPoint[x])
                AddToCompBiconexe(make_pair(x,y));
        }
        else if(y!=tx){
            low[x]=min(low[x],dnum[y]);
        }
    }


}

int main()
{
    Read();
    DFS(1,0);
    out<<ComponenteBiconexe.size()<<"\n";
    for(auto c:ComponenteBiconexe){
        for(auto e:c )
            out<<e<<" ";
        out<<"\n";
    }

    return 0;
}