#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;
#define x first
#define y second
#define dbg(x) cout << #x << '=' << x << '\n';
#define ll long long
#define pi pair<int,int>
#define pl pair<ll,ll>
#define pd pair<double,double>
#define ld long double
#define pld pair<ld,ld>
#define lg length()
#define sz size()
#define pb push_back
#define MAXN 100005
#define INF 1000000005
#define LINF 1000000000000000005
#define x1 xdddddddddddddddddd
#define y1 ydddddddddddddddddd

int n,m,h[100005],p[100005],x,y,v[100005],t;

vector <int> g[100005];

set <int> s[100005];

vector <pi> q;

void DFS(int nod, int pr){
    v[nod]=1;
    if(pr!=-1) h[nod]=h[pr]+1;
    p[nod]=h[nod];
    for(int i : g[nod]){
        if(!v[i]){
            q.pb({nod,i});
            DFS(i,nod);
            p[nod]=min(p[nod],p[i]);
            if(p[i]>=h[nod]){
                t++;
                while(q.sz){
                    pi j=q[q.sz-1];
                    s[t].insert(j.x);
                    s[t].insert(j.y);
                    q.pop_back();
                    if(j.x==nod && j.y==i) break;
                }
            }
        }
        else if(i!=pr){
            p[nod]=min(p[nod],h[i]);
        }
    }
}

int32_t main(){
    ios_base :: sync_with_stdio(0); cin.tie(); cout.tie();
    ifstream cin("biconex.in");
    ofstream cout("biconex.out");
    cin >> n >> m;
    for(int i=1;i<=m;i++){
        cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
    }
    for(int i=1;i<=n;i++){
        if(!v[i]) DFS(i,-1);
    }
    cout << t << '\n';
    for(int i=1;i<=t;i++){
        for(int j : s[i]) cout << j << ' ';
        cout << '\n';
    }
}