#include <bits/stdc++.h>

#define pii pair<int,int>
#define eb emplace_back
//#define ll long long
#define pll pair<ll,ll>
using namespace std;

int n,m;
const int NMAX = 1e5+1;
vector<int> G[NMAX],d(NMAX,-1),low(NMAX,-1);
bitset<NMAX> art;
int nr_comp_biconex, timp, nrfii,start;
stack <pii> St;
set<int> Comp[NMAX];


void afisare_comp_biconex(int x, int y){
    nr_comp_biconex++;
    pii p;
    do{
        p = St.top();St.pop();
        Comp[nr_comp_biconex].insert(p.first);
        Comp[nr_comp_biconex].insert(p.second);
    }while(p.first!=x || p.second!=y);
}
void dfs(int x, int p = -1){
    d[x] = low[x] = ++timp;
    for(int y : G[x]){
        if(y!= p && d[x] > d[y]) St.push({x,y});

        if(d[y]==-1){
            if(x == start) nrfii++;
            dfs(y,x);
            low[x] = min(low[x],low[y]);
            if(low[y]>=d[x]){
                if(x != start) art[x] = true;
                afisare_comp_biconex(x,y);
            }
        }else if(y != p) low[x] = min( low[x],d[y]);
    }
}

int main() {
    ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    cin>>n>>m;
    for(int i=1;i<=m;i++){
        int x,y;
        cin>>x>>y;
        G[x].eb(y);G[y].eb(x);
    }
    St.push({1,-1});
    start=1;
    dfs(1);
    cout<<nr_comp_biconex<<'\n';
    for(int i=1;i<=nr_comp_biconex;i++){
        for(auto j : Comp[i]) cout<<j<<' ';
        cout<<'\n';
    }

    return 0;
}