#include <fstream>
using namespace std;

ofstream g ("biconex.out");
const int MAXN = 100005;
int n, m, niv[MAXN], minniv[MAXN], lg[MAXN], vf, nr, cnt;

struct nod
{
    int x;
    nod *leg;
};
nod *v[MAXN * 2], *c[MAXN * 2];
struct muchie
{
    int x, y;
} st[MAXN * 2];

void add (nod *&dest, int vf)
{
    nod *p;
    p = new nod;
    p -> x = vf;
    p -> leg = dest;
    dest = p;
}

void citire()
{
    ifstream f ("biconex.in");
    f >> n >> m;
    int i, x, y;
    for (i = 1; i <= m; i++)
    {
        f >> x >> y;
        add (v[x], y);
        add (v[y], x);
    }
    f.close();
}

void tarjan (int x, int y)
{
    //niv[x] = nivelul lui x in arborele de cautare
    //minniv[x] = nivelul minim la care se poate ajunge din x
    niv[x] = minniv[x] = nr;
    nr++;

    nod *p;
    for (p = v[x]; p != NULL; p = p -> leg)
    {
        if (y == p->x) continue;
        if (niv[p->x] == -1)
        {
            ++vf;
            st[vf].x = x, st[vf].y = p->x;
            tarjan (p->x, x);
            minniv[x] = min (minniv[x], minniv[p->x]);
            if (minniv[p->x] >= niv[x])
            {
                cnt++;
                do
                {
                    add (c[cnt], st[vf].x);
                    add (c[cnt], st[vf].y);
                    lg[cnt] += 2;
                    vf--;
                }
                while (vf > 0 && (x != st[vf + 1].x || p->x != st[vf + 1].y) );
            }
        }
        else
            minniv[x] = min (minniv[x], niv[p->x]);
    }


}

int main()
{
    citire();
    for (int i = 1; i <= n; i++) niv[i] = -1;
    nr = vf = 0;
    for (int i = 1; i <= n; i++)
        if (niv[i] == -1)
            tarjan (i, 0);

    g << cnt << '\n';
    for (int i = 1; i <= cnt; i++)
    {
        bool viz[lg[i] + 1];
        for (int i = 0; i <= lg[i]; i++) viz[i] = false;
        for (nod *p = c[i]; p != NULL; p = p->leg)
        {
            if (!viz[p->x])
            {
                g << p->x << ' ';
                viz[p->x] = true;
            }
        }
        g << '\n';
    }
    return 0;
}