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

using namespace std;

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

const int nMax = 100000;
const int oo = 200000000;
int n, m;
vector<int> g[nMax + 5];
vector<vector<int>> sol;
stack<int> st;
int low[nMax + 5], niv[nMax + 5];
int use[nMax + 5];

void Add(int tt, int fiu) {
    vector<int> step;
    while (st.top() != fiu) {
        step.push_back(st.top());
        st.pop();
    }
    step.push_back(fiu);
    step.push_back(tt);
    st.pop();
    sol.push_back(step);

}

void DFS(int nod, int tt) {
    use[nod] = 1;
    for (auto i : g[nod]) {
        if (i == tt)
            continue;
        if (use[i] == 1)
            low[nod] = min(low[nod], niv[i]);
        else {
            st.push(i);
            niv[i] = niv[nod] + 1;
            DFS(i, nod);
            low[nod] = min(low[nod], low[i]);
            if (low[i] >= niv[nod])
                Add(nod, i);
        }
    }
}

int main() {
    fin >> n >> m;
    for (int i = 1; i <= n; i++) {
        low[i] = oo;
    }
    for (int i = 1; i <= m; i++) {
        int x, y;
        fin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    for (int i = 1; i <= n; i++)
        if (use[i] == 0)
            DFS(i, 0);
    fout << sol.size() << '\n';
    for (int i = 0; i <sol.size(); i++) {
        for (auto j : sol[i])
            fout << j << " ";
        fout << '\n';
    }
}