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

#define MaxNodes 100001

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

int n, m, x1, x2;
vector<vector<int> > G, comp;
vector<int> c;
stack<pair<int, int> > s;
int nv[MaxNodes];
int l[MaxNodes];
bool v[MaxNodes];

void Read();
void Df(int x, int t, int niv);
void Write();

int main()
{
    Read();
    Df(1, 0, 0);
    Write();
    is.close();
    os.close();
    return 0;
}

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

void Df(int x, int t, int niv)
{
    nv[x] = l[x] = niv;
    v[x] = true;
    for ( const auto& y : G[x] )
    {
        if ( y == t ) continue;
        if ( !v[y] )
        {
            s.push({x, y});
            Df(y, x, niv + 1);
            l[x] = min(l[x], l[y]);
            if ( l[y] >= nv[x] )
            {
                c.clear();
                do
                {
                    x1 = s.top().first;
                    x2 = s.top().second;
                    s.pop();
                    c.push_back(x1);
                    c.push_back(x2);
                } while ( x1 != x && x2 != y );
                comp.push_back(c);
            }
        }
        else
            l[x] = min(l[x], nv[y]);
    }
}

void Write()
{
    os << comp.size() << '\n';
    for ( auto& c : comp )
    {
        sort(c.begin(), c.end());
        c.erase(unique(c.begin(), c.end()), c.end());
        for ( const auto& t : c )
            os << t << ' ';
        os << '\n';
    }
}