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

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

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

void READ();
void CB(int x);
void MAKE(int x, int y);

int main()
{
    READ();
    nv[1] = nm[1] = 1;
    CB(1);
    os << cb.size() << "\n";
    for ( auto c : cb )
    {
        for ( auto i : c )
            os << i << " ";
        os << "\n";
    }
    is.close();
    os.close();
    return 0;
}

void CB(int x)
{
    for ( auto y : g[x] )
    {
        if ( t[x] == y )
            continue;
        if ( !nv[y] )
        {
            t[y] = x;
            s.push(make_pair(x, y));
            nv[y] = nm[y] = nv[x] + 1;
            CB(y);
            nm[x] = min(nm[x], nm[y]);
            if ( nm[y] >= nv[x] )
                MAKE(x, y);
        }
        else
            nm[x] = min(nm[x], nv[y]);
    }
}

void MAKE(int x, int y)
{
    c.clear();
    int xx, yy;
    do
    {
        xx = s.top().first;
        yy = s.top().second;
        s.pop();
        c.push_back(xx);
        c.push_back(yy);
    } 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 a, b;
    is >> n >> m;
    g.resize(n + 1);
    t.resize(n + 1);
    nv.resize(n + 1);
    nm.resize(n + 1);
    for ( int i = 1; i <= m; ++i )
    {
        is >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
}