#include <bits/stdc++.h>
#define pb push_back
#define pii pair<int,int>

using namespace std;

ifstream fin("biconex.in");
ofstream fout("biconex.out");

const int nmax=1e5;

vector<int>v[nmax+1],c[nmax+1];
int d[nmax+1],low[nmax+1],timer,comp;

stack<pii>stk;

void get_bcc(pii e){
    comp++;
    pii t;
    do{
        t=stk.top();
        stk.pop();
        c[comp].pb(t.first);
        c[comp].pb(t.second);
    }while(stk.size() && t!=e);
}

void tarjan(int nod,int pr){
    int cnt=0;
    d[nod]=low[nod]=++timer;
    for(int i:v[nod]){
        if(i==pr)
            continue;
        if(d[i])
            low[nod]=min(low[nod],d[i]);
        else{
            stk.push({nod,i});
            cnt++;
            tarjan(i,nod);
            low[nod]=min(low[nod],low[i]);
            if((low[i]>=d[nod] && nod!=1) || (nod==1 && cnt>=2))
                get_bcc({nod,i});
        }
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n,m;
    fin>>n>>m;
    while(m--){
        int st,dr;
        fin>>st>>dr;
        v[st].pb(dr);
        v[dr].pb(st);
    }
    for(int i=1;i<=n;i++)
        if(!d[i])
            tarjan(i,i);
    get_bcc({0,0});
    fout<<comp<<'\n';
    for(int i=1;i<=comp;i++){
        sort(c[i].begin(),c[i].end());
        c[i].erase(unique(c[i].begin(),c[i].end()),c[i].end());
        for(int j:c[i])
            fout<<j<<' ';
        fout<<'\n';
    }
    return 0;
}