#include<fstream>
#include<vector>
//#include<iostream>
#include<stack>
#define pb push_back
#define st s.top()
using namespace std;
ifstream in("biconex.in");
ofstream out("biconex.out");
int N,M,t[100005],niv[100005],l[100005],u,af[100005],mm;
bool viz[100005];
vector<int> v[100005];
vector< pair<int,int> > sol[200005];
vector< pair<int,int> > :: iterator it;
stack< pair<int,int> > s;
void df(int i);
int main()
{
    in>>N>>M;
    int i,a,b;
    for(i=1;i<=M;++i)
    {
        in>>a>>b;
        v[a].pb(b);
        v[b].pb(a);
    }
    df(1);
    out<<u<<'\n';
    for(i=1;i<=u;++i)
    {
        for(it=sol[i].begin();it!=sol[i].end();++it)
        {
            if(af[it->first]!=i)
            out<<it->first<<' ',af[it->first]=i;
            if(af[it->second]!=i)
            out<<it->second<<' ',af[it->second]=i;
        }
        out<<'\n';
    }
    //cout<<mm;
}
void df(int i)
{
    vector<int> :: iterator it;
    viz[i]=1;
    niv[i]=niv[t[i]]+1;
    l[i]=niv[i];
    for(it=v[i].begin();it!=v[i].end();++it)
    if(*it!=t[i])
    {
        //s.push(make_pair(i,*it));
        if(viz[*it])
        {
            if(l[i]>niv[*it])
            {
                l[i]=niv[*it];
                //LINIA URMATOARE E PROBLEMA
                s.push(make_pair(i,*it));
                //++mm;
            }
        }
        else
        {
            t[*it]=i;
            s.push(make_pair(i,*it));
            //++mm;
            df(*it);
            l[i]= l[*it]<l[i] ? l[*it] : l[i];
            if(l[*it]>=niv[i])
            {
                ++u;
                while(st.first!=i && st.second!=*it)
                {
                    //cout<<'('<<st.first<<';'<<st.second<<')'<<' ';
                    sol[u].push_back(st);
                    s.pop();
                }
                //cout<<'('<<st.first<<';'<<st.second<<')'<<' ';
                sol[u].push_back(st);
                s.pop();
                //cout<<'\n';
            }
        }

    }
}