#include <bits/stdc++.h>
#define N 100005
#define cin fin
#define cout fout
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
bool viz[N];
int nivel[N],nma[N],x,y,n,m,i,nr;
vector<int> sol[N],v[N];
stack<int> s;
void dfs(int nod,int tata)
{
    viz[nod]=1;
    s.push(nod);
    nivel[nod]=nivel[tata]+1;
    nma[nod]=nivel[nod];
    for(auto x:v[nod])
    {
        if(x==tata) continue;
        if(viz[x]==1) nma[nod]=min(nma[nod],nivel[x]);
        else
        {
            dfs(x,nod);
            nma[nod]=min(nma[nod],nma[x]);
            if(nivel[nod]<=nma[x])
            {
                nr++;
                while(!s.empty()&&s.top()!=x)
                {
                    sol[nr].push_back(s.top());
                    s.pop();
                }
                sol[nr].push_back(x);
                s.pop();
                sol[nr].push_back(nod);
            }

        }
    }
}
int main()
{
    cin>>n>>m;
    for(i=1; i<=n; i++)
    {
        cin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(i=1; i<=n; i++)
    {
        if(viz[i]==0)
        {
            dfs(i,0);
        }
    }
    cout<<nr<<'\n';
    for(i=1;i<=nr;i++)
    {
        for(auto x:sol[i]) cout<<x<<' ';
        cout<<'\n';
    }
    return 0;
}