#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <stack>
#include <set>
#include <stdio.h>
using namespace std;

#define NMAX 100001

vector <int> v[NMAX];
set <int> sol[2 * NMAX];
int viz[NMAX], low[NMAX], lev[NMAX], nr;
stack <pair <int, int> > st;

void bc(int nod, int x) {
    int a, b;
    nr++;
    do {
        a = st.top().first;
        b = st.top().second;
        sol[nr].insert(a);
        sol[nr].insert(b);
        st.pop();
    } while (a != nod || x != b);
}

void dfs(int nod, int niv, int p) {
    viz[nod] = 1;
    lev[nod] = niv;
    low[nod] = niv;
    for (const int x : v[nod]) {
        if (viz[x] == 0) {
            st.push(make_pair(nod, x));
            dfs(x, niv + 1, nod);
            low[nod] = min(low[nod], low[x]);
            if (low[x] >= niv) {
                bc(nod, x);
            }
        } else if (x != p) {
            low[nod] = min(low[nod], lev[x]);
        }
    }
}

int main()
{
    ios::sync_with_stdio(false);

    int n, m;
    ifstream f("biconex.in");
    ofstream g("biconex.out");
    f >> n >> m;
    for (int i = 1; i <= m; i++) {
        int x,  y;
        f >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    f.close();

    for (int i = 1; i <= n; i++) {
        if (viz[i] == 0)
            dfs(i, 0, 0);
    }

    g << nr << '\n';
    for (int i = 1; i <= nr; i++) {
        for (const int x : sol[i]) {
            g << x << " ";
        }
        g << '\n';
    }
    g.close();

    return 0;
}