#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
using namespace std;

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

int n, m;
vector<int> nv, nm, t, c;
vector<vector<int>> g, cb;
stack<pair<int, int>> s;

void Read();
void Solve(int nod);
void Write();
void Make(int x, int y);

int main()
{
    Read();
    for ( int i = 1; i <= n; ++i )
        if ( !nv[i] )
        {
            nv[i] = nm[i] = 1;
            Solve(i);
        }
    Write();
    is.close();
    os.close();
    return 0;
}

void Solve(int nod)
{
    for ( const auto& nodv : g[nod] )
    {
        if ( t[nod] == nodv )
            continue;
        if ( !nv[nodv] )
        {
            t[nodv] = nod;
            nv[nodv] = nm[nodv] = nv[nod] + 1;
            s.push(make_pair(nod, nodv));
            Solve(nodv);
            nm[nod] = min(nm[nod], nm[nodv]);
            if ( nm[nodv] >= nv[nod] )
                Make(nod, nodv);
        }
        else
            nm[nod] = min(nm[nod], nv[nodv]);
    }
}

void Make(int x, int y)
{
    c.clear();
    int xx, yy;
    do
    {
        c.push_back(xx = s.top().first);
        c.push_back(yy = s.top().second);
        s.pop();
    } while ( xx != x && yy != y );
    sort(c.begin(), c.end());
    c.erase(unique(c.begin(), c.end()), c.end());
    cb.push_back(c);
}

void Read()
{
    int n1, n2;
    is >> n >> m;
    g.resize(n + 1);
    nv.resize(n + 1);
    nm.resize(n + 1);
    t.resize(n + 1);
    for ( int i = 1; i <= m; ++i )
    {
        is >> n1 >> n2;
        g[n1].push_back(n2);
        g[n2].push_back(n1);
    }
}

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