#include <bits/stdc++.h>
using namespace std;
ifstream in("biconex.in");
ofstream out("biconex.out");
vector <int> v[100005];
int nivel[100005], nma[100005], vis[100005];
stack <int> s;
vector <int> temp;
vector < vector <int> > biconexe;
void f(int k, int parent)
{
    vis[k] = 1;
    nivel[k] = nivel[parent] + 1;
    nma[k] = nivel[k];
    s.push(k);
    for(int x : v[k])
    {
        if(x == parent)
            continue;
        if(vis[x])
        {
            if(nma[k] > nivel[x])
                nma[k] = nivel[x];
        }
        else
        {
            f(x, k);
            if(nma[k] > nma[x])
                nma[k] = nma[x];
            if(nivel[k] <= nma[x])
            {
                while(s.top() != x)
                {
                    temp.push_back(s.top());
                    s.pop();
                }
                s.pop();
                temp.push_back(x);
                temp.push_back(k);
                biconexe.push_back(temp);
                temp.clear();
            }
        }
    }
}

int main()
{
    int n, m, x, y;
    in >> n >> m;
    for(int i = 1; i <= m; i ++)
    {
        in >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    f(1, 0);
    out << biconexe.size() << '\n';
    for(auto i : biconexe)
    {
        for(int j : i)
            out << j << " ";
        out << '\n';
    }
    return 0;
}