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

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

vector<vector<int> > G;
stack<pair<int, int> > E;
vector<int> L, Lvl;
set<int> Comp[100001];
int n, k, m;

void Read();
void Extract(int x, int y);
void Df(int node, int t, int lvl);

int main()
{
    Read();
    Df(1, 0, 1);

    os << k << '\n';

    for ( int i = 1; i <= k; ++i )
    {
        for ( const auto& c : Comp[i] )
            os << c << ' ';
        os << '\n';
    }


    is.close();
    os.close();
    return 0;
}



void Extract(int x, int y)
{
    int node, vec;
    do
    {
        node = E.top().first;
        vec = E.top().second;
        E.pop();
        Comp[k].insert(node);
        Comp[k].insert(vec);
    } while ( x != node || y != vec );
}

void Df(int node, int t, int lvl)
{
    Lvl[node] = L[node] = lvl;
    for ( const auto& g : G[node] )
    {
        if ( g == t )
            continue;
        if ( !Lvl[g] )
        {
            E.push({node, g});
            Df(g, node, lvl + 1);
            L[node] = min(L[node], L[g]);
            if ( L[g] >= Lvl[node] )
            {
                ++k;
                Extract(node, g);
            }
        }
        else
            L[node] = min(L[node], Lvl[g]);
    }
}

void Read()
{
    is >> n >> m;
    G = vector<vector<int> >(n + 1);
    Lvl = L = vector<int>(n + 1);
    int x, y;
    for ( int i = 1; i <= m; ++i )
    {
        is >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
}