#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
#define INF 0x3f3f3f3f
using namespace std;

ifstream is("biconex.in");
ofstream os("biconex.out");

using VI = vector<int>;
using VVI = vector<VI>;

int n, m, cnt;
VI c, nv, nm, t;
VVI g, ctc;
stack<pair<int, int>> s;
void Read();
void Write();
void Solve(int nod);

int main()
{
    Read();
    nv = nm = t = VI(n + 1);
    Solve(1);
    Write();
    is.close();
    os.close();
    return 0;
}

void Solve(int nod)
{
    nv[nod] = nm[nod] = ++cnt;
    for ( const auto &nodv : g[nod] )
    {
        if ( t[nod] == nodv )
            continue;
        if ( !nv[nodv] )
        {
            s.push(make_pair(nod, nodv));
            t[nodv] = nod;
            Solve(nodv);
            nm[nod] = min(nm[nod], nm[nodv]);
            if ( nm[nodv] >= nv[nod] )
            {
                c.clear();
                int n1, n2;
                do {
                    c.push_back(n1 = s.top().first);
                    c.push_back(n2 = s.top().second);
                    s.pop();
                }
                while ( n1 != nod && n2 != nodv );
                sort(c.begin(), c.end());
                c.erase(unique(c.begin(), c.end()), c.end());
                ctc.push_back(c);
            }
        }
        else
            nm[nod] = min(nm[nod], nv[nodv]);
    }
}

void Read()
{
    is >> n >> m;
    g = VVI(n + 1);
    int x, y;
    while ( m-- )
    {
        is >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
}

void Write()
{
    os << ctc.size() << "\n";
    for ( const auto &i : ctc )
    {
        for ( const auto &j : i )
            os << j << " ";
        os << "\n";
    }
}