#include <bits/stdc++.h>
#define nmax 200001
using namespace std;
int n, m;
vector <int> v[nmax];
int dfn[nmax], low[nmax], num;
vector <pair <int, int> > s;
set <int> sol[nmax];
int q;
void init()
{
    int i;
    for (i=1; i<=n; ++i) dfn[i]=low[i]=-1;
    s.push_back(make_pair(1,-1));
}
void afis(int x, int u)
{
    q++;
    int tmp1, tmp2;
    do
    {
        tmp1=s.back().first;
        tmp2=s.back().second;
        s.pop_back();
        sol[q].insert(tmp1); sol[q].insert(tmp2); }
        while (tmp1!=x || tmp2!=u);

}
void biconex (int u, int tu)
{
    int x, i;
    dfn[u]=low[u]=++num;
    vector <int> :: iterator it;
    for (it=v[u].begin();it!=v[u].end();++it)
    {
        x=(*it);
        if (x!=tu && dfn[x] < dfn[u])
            s.push_back(make_pair(x,u));
            if (dfn[x]==-1) {
                biconex(x,u);
            low[u]=min(low[u],low[x]);
            if (low[x] >= dfn[u])
                afis(x,u);
            }
            else if (x!=tu)
            {
                low[u]=min(low[u],dfn[x]);
            }

    }

}
int main()
{
    ifstream f("biconex.in");
    ofstream g("biconex.out");
    int m, x, y, i;
    f >> n >> m;
    for (i=1; i<=m; ++i)
    {
        f >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }

    init();
    biconex(1,-1);
    g << q << "\n";
    for (i=1; i<=q; ++i)
    {
        for (set <int> :: iterator it=sol[i].begin();it!=sol[i].end();++it)
            g << *it << " ";
        g <<"\n";
    }
    return 0;
}