#include <bits/stdc++.h>
#define NMAX 100010
#define pb push_back
using namespace std;

ifstream f("biconex.in");
ofstream g("biconex.out");

int n, m, y, x, cate;
deque <int> Q;
bitset <NMAX> viz;
int low[NMAX], niv[NMAX];
vector <int> G[NMAX], sol[NMAX];

void DFS(int nod, int dad)
{
    viz[nod] = 1;
    Q.push_back(nod);
    low[nod] = niv[nod];

    for(auto it : G[nod])
    {
        if(it == dad)
            continue;
        if(viz[it])
        {
            low[nod] = min(low[nod], niv[it]);
            continue;
        }

        niv[it] = niv[nod] + 1;
        DFS(it, nod);
        low[nod] = min(low[nod], low[it]);
        if(low[it] >= niv[nod])
        {
            cate++;
            int u;
            do{
                u = Q.back();
                Q.pop_back();
                sol[cate].push_back(u);
            }while(!Q.empty() && u != it);
        }
        sol[cate].push_back(nod);
    }
}

int main()
{
    f >> n >> m;
    for(int i = 1; i <= m; ++i)
    {
        f >> x >> y;
        G[x].pb(y);
        G[y].pb(x);
    }
    DFS(1,0);
    g << cate << '\n';
    for(int i = 1; i <= cate; ++i, g << '\n')
        for(int j = 0; j < sol[i].size(); ++j)
            g << sol[i][j] << ' ';
    f.close();
    g.close();
    return 0;
}