#include<stack>
#include<cstdio>
#include<vector>
#include<algorithm>

using namespace std;

int N, M, dp[100009], niv[100009];
vector < vector < int > > comps;
vector < int > v[100009];
stack < pair < int , int > > S;

void unify (vector < int > &v)
{
    sort (v.begin (), v.end ());
    v.erase (unique (v.begin (), v.end ()), v.end ());
}

void Add_Component (pair < int , int > nd)
{
    pair < int , int > top;
    vector < int > comp;
    do
    {
        top = S.top ();
        comp.push_back (top.first);
        comp.push_back (top.second);
        S.pop ();
    }while (top != nd);
    unify (comp);
    comps.push_back (comp);
}

void dfs (int nod, int tata)
{
    dp[nod] = niv[nod];
    for (vector < int > :: iterator it = v[nod].begin (); it != v[nod].end (); it ++)
    if (niv[*it] == 0)
    {
        niv[*it] = niv[nod] + 1;
        S.push (make_pair (nod, *it));
        dfs (*it, nod);
        if (dp[*it] > niv[nod]) ;///muchie ciritca
        if (dp[*it] >= niv[nod]) Add_Component (make_pair (nod, *it));///nod este critic
    }

    bool deja = 0;
    for (vector < int > :: iterator it = v[nod].begin (); it != v[nod].end (); it ++)
    {
        if (*it == tata && deja == 0) deja = 1;
        else
        if (dp[*it] < dp[nod]) dp[nod] = dp[*it];
    }
}
int main ()
{
freopen ("biconex.in", "r", stdin);
freopen ("biconex.out", "w", stdout);

scanf ("%d %d", &N, &M);
while (M)
{
    M --;
    int x, y;
    scanf ("%d %d", &x, &y);
    v[x].push_back (y);
    v[y].push_back (x);
}

niv[1] = 1;
dfs (1, 0);

printf ("%d\n", comps.size ());
for (int i=0; i<comps.size (); i++, printf ("\n"))
    for (vector < int > :: iterator it = comps[i].begin (); it != comps[i].end (); it ++)
        printf ("%d ", *it);

return 0;
}