#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

const int N = 1e5 + 5;
int n, m, lvl[N], low[N];
vector<int> v[N];
bool viz[N], art[N];
set<int> comp;
set<pair<int, int>> muchii;
vector<set<int>> componente;

void DFS1(int nod, int niv)
{
    viz[nod] = 1;
    lvl[nod] = niv;
    low[nod] = niv;
    for (int i : v[nod])
        if (!viz[i])
        {
            DFS1(i, niv + 1);
            low[nod] = min(low[nod], low[i]);
        }
        else if (i != nod)
        {
            low[nod] = min(low[nod], lvl[i]);
        }
}

void DFS2(int nod)
{
    viz[nod] = 1;
    comp.insert(nod);
    for (int i : v[nod])
        if (!viz[i])
        {
            if (art[i])
                comp.insert(i);
            else
                DFS2(i);
        }
}

void inserare(int x, int y)
{
    muchii.insert({min(x, y), max(x, y)});
}

int main()
{
    fin >> n >> m;
    while (m--)
    {
        int a, b;
        fin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for (int i = 1; i <= n; i++)
        low[i] = 1e9;
    DFS1(1, 0);
    for (int i = 1; i <= n; i++)
        viz[i] = 0;
    for (int i = 1; i <= n; i++)
        for (int fiu : v[i])
            art[i] |= (low[fiu] >= lvl[i]);
    for (int i = 1; i <= n; i++)
        if (!viz[i] && !art[i])
        {
            comp.clear();
            DFS2(i);
            componente.push_back(comp);
            for (int nod : comp)
                for (int fiu : v[nod])
                    if (comp.find(fiu) != comp.end())
                        inserare(nod, fiu);
        }
    for (int i = 1; i <= n; i++)
        if (art[i])
            for (int fiu : v[i])
                if (art[fiu] && fiu < i &&
                    muchii.find({min(i, fiu), max(i, fiu)}) == muchii.end())
                {
                    componente.push_back({i, fiu});
                    inserare(i, fiu);
                }
    fout << componente.size() << '\n';
    for (set<int> &s : componente)
    {
        for (int i : s)
            fout << i << ' ';
        fout << '\n';
    }
}