#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <stack>

using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");

int n, m, nr, root;

vector<vector<int>> G, Cb;
vector<int> niv, L, t, c;
vector<bool> p_art;
stack<int> st;

void Read();
void Tarjan(int x, int nv);
void Mark();

int main()
{
    Read();
    root = 1;
    Tarjan(root, 1);
    int x, y;
    Mark();
    while(!st.empty())
    {
        x = st.top();
        st.pop();
        y = p_art[t[x]];
        c.push_back(x);
        if( y == 1 )
        {
            c.push_back(t[x]);
            Cb.push_back(c);
            c.clear();
        }
    }
    if ( c.size() != 1 )
        Cb.push_back(c);
        fout << Cb.size() << '\n';;
    for ( auto g : Cb )
    {
        for ( auto z : g )
            fout << z << ' ';
        fout << '\n';
    }
    return 0;
}

void Read()
{
    fin >> n >> m;
    int x, y;
    G = vector<vector<int>>(n + 1);
    niv = vector<int>(n + 1);
    L = vector<int>(n + 1);
    p_art = vector<bool>(n + 1);
    t = vector<int>(n + 1);
    for ( int i = 1; i <= m; i++)
    {
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
}
void Tarjan(int x, int nv)
{
    if ( nv == 2 )
        nr++;
    st.push(x);
    L[x] = niv[x] = nv;
    for ( auto y : G[x] )
    {
        if ( !niv[y] )
        {
            t[y] = x;
            Tarjan(y, nv + 1);
            L[x] = min(L[y], L[x]);
        }
        else
            if ( t[x] != y )
                L[x] = min(L[x], niv[y]);
    }
}
void Mark()
{
    for ( int i = 1; i <= n; i++ )
    {
        if ( !t[i] )
        {
            if (  nr > 1)
                p_art[i] = 1;
            //fout << i << ' ';
            continue;
        }
        if ( L[i] >= niv[t[i]] && t[i] != root )
        {
            p_art[t[i]] = 1;
            //, fout << i << ' ';
        }
    }
//fout << "tati:\n";
//	int i;
//	for ( i = 1; i <= n; i++ )
//		fout << t[i] << " ";
//
//	fout << "\nniv\n";
//	for ( i = 1; i <= n; i++ )
//		fout << niv[i] << " ";
//
//	fout << "\nl:\n";
//	for ( i = 1; i <= n; i++ )
//		fout << L[i] << " ";
//	fout << "\n";
//
//	fout << "punctele de articulatie:\n";
//	for ( i = 1; i <= n; i++ )
//		if ( p_art[i] ) fout << i << " ";
}