#include <fstream>
#include <vector>
#include <stack>

using namespace std;

const int N = 1e5;

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

vector <int> a[N+1];
vector <int> cbc[N+1];
stack <int> stiva;
vector <int> t_min, t_in;
int timp, ncbc;

void adauga_componenta(int x, int y)
{
    ++ncbc;
    while (stiva.top() != y)
    {
        cbc[ncbc].push_back(stiva.top());
        stiva.pop();
    }
    cbc[ncbc].push_back(stiva.top());
    stiva.pop();
    cbc[ncbc].push_back(x);
}

void dfs(int x, int t)
{
    t_in[x] = t_min[x] = ++timp;
    stiva.push(x);
    for (auto y: a[x])
    {
        if (y == t)
        {
            continue;
        }
        if (t_in[y] == 0)
        {
            dfs(y, x);
            t_min[x] = min(t_min[x], t_min[y]);
            if (t_min[y] >= t_in[x])
            {
                adauga_componenta(x, y);
            }
        }
        else
        {
            t_min[x] = min(t_min[x], t_in[y]);
        }
    }
}

int main()
{
    int n, m;
    in >> n >> m;
    for (int i = 0; i < m; i++)
    {
        int x, y;
        in >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    t_min.reserve(n + 1);
    t_min.resize(n + 1);
    fill(t_min.begin(), t_min.end(), 0);
    t_in.reserve(n + 1);
    t_in.resize(n + 1);
    fill(t_in.begin(), t_in.end(), 0);
    for (int i = 1; i <= n; i++)
    {
        if (t_in[i] == 0)
        {
            dfs(i, 0);
        }
    }
    out << ncbc << "\n";
    for (int i = 1; i <= ncbc; i++)
    {
        for (auto x: cbc[i])
        {
            out << x << " ";
        }
        out << "\n";
    }
    in.close();
    out.close();
    return 0;
}