#include <iostream>
#include <fstream>
#include <stack>
#include <vector>
#include <deque>
#include <ctime>
#include <queue>

#define ll long long
#define ull unsigned long long
#define pb push_back
using zint = int;
using namespace std;
const int inf = 1e9 + 5;
const int NMax = 1e5 + 5;
ifstream in("biconex.in");
ofstream out("biconex.out");

int N,M,nrComp;
bool vis[NMax];
int lowpoint[NMax],depth[NMax];
vector<int> v[NMax],comp[NMax];
stack< pair<int,int> > st;

void dfs(int,int);
void getComp(pair<int,int>);

int main() {
    in>>N>>M;
    for (int i=1;i <= M;++i) {
        int x,y;
        in>>x>>y;

        v[x].pb(y);
        v[y].pb(x);
    }

    dfs(1,0);

    out<<nrComp<<'\n';
    for (int i=1;i <= nrComp;++i) {
        for (int node : comp[i]) {
            out<<node<<' ';
        }
        out<<'\n';
    }

    in.close();out.close();
    return 0;
}

void dfs(int node,int dad) {
    st.push( pair<int,int>(dad,node) );

    lowpoint[node] = depth[node] = depth[dad] + 1;
    for (int nxt : v[node]) {
        if (depth[nxt]) {
            lowpoint[node] = min(lowpoint[node],depth[nxt]);
        }
        else {
            dfs(nxt,node);

            lowpoint[node] = min(lowpoint[node],lowpoint[nxt]);
            if (lowpoint[nxt] == depth[node]) {
                ++nrComp;
                getComp( pair<int,int> (node,nxt) );
            }
        }
    }
}

void getComp( pair<int,int> p ) {
    pair<int,int> aux;

    while (true) {
        aux = st.top(); st.pop();
        comp[nrComp].pb(aux.second);

        if (aux == p) {
            break;
        }
    }
    comp[nrComp].pb(aux.first);
}