#include <fstream>
#include <iostream>
#include <vector>
#include <stack>
#include <algorithm>
#define nmax 100005

using namespace std;

FILE *fi, *fo;
int n, m, nrComp;
int tata[nmax], low[nmax], nivel[nmax];
stack < pair<int, int> > s;
vector <int> G[nmax], sol[nmax];
bool viz[nmax];

void newComp(int x, int y)
{
    int X = s.top().first;
    int Y = s.top().second;
    s.pop();
    while (X != x && Y != y)
    {
        sol[nrComp].push_back(X);
        sol[nrComp].push_back(Y);
        X = s.top().first;
        Y = s.top().second;
        s.pop();
    }
    sol[nrComp].push_back(X);
    sol[nrComp].push_back(Y);
}

void dfs(int nod)
{
    viz[nod] = true;
    for (int i = 0; i < G[nod].size(); i++)
    {
        int vecin = G[nod][i];
        if (!viz[vecin])
        {
            low[vecin] = nivel[vecin] = nivel[nod] + 1;
            tata[vecin] = nod;
            s.push(make_pair(nod, vecin));
            dfs(vecin);
            low[nod] = min(low[nod], low[vecin]);
            if (low[vecin] >= nivel[nod])
            {
                nrComp++;
                newComp(nod, vecin);
            }
        }
        else if (tata[nod] != vecin)
            low[nod] = min(low[nod], nivel[vecin]);
            
    }
}

int main()
{
    
    ifstream fi("biconex.in");
    ofstream fo("biconex.out");
    
    fi >> n >> m;
    
    for (int i = 1; i <= m; i++)
    {
        int x, y;
        fi >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    
    dfs(1);
    
    fo << nrComp << "\n";
    for (int i = 1; i <= nrComp; i++)
    {
        sort(sol[i].begin(), sol[i].end());
        fo << sol[i][0] << " ";
        for (int j = 1; j < sol[i].size(); j++)
            if (sol[i][j] != sol[i][j-1])
                fo << sol[i][j] << " ";
        fo << "\n";
    }
    
    fi.close();
    fo.close();
    
    return 0;
}