#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),low(NMAX), Comp[NMAX], St;
int nr, timp;

void dfs(int x, int p = -1){
    d[x] = low[x] = ++timp;
    St.push_back(x);
    for(int y : G[x]){
        if(y == p) continue;
        if(d[y]){
            low[x] = min(low[x],d[y]);
        }else{
            dfs(y,x);
            low[x] = min(low[x],low[y]);
            if(low[y]>=d[x]){
                nr++;
                while(!St.empty() && St.back()!=y){
                    Comp[nr].push_back(St.back());St.pop_back();
                }
                Comp[nr].push_back(St.back());
                Comp[nr].push_back(x);
                St.pop_back();
            }
        }
    }
}

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);
    }
    dfs(1);
    cout<<nr<<'\n';
    for(int i=1;i<=nr;i++){
        sort(Comp[i].begin(),Comp[i].end());
        for(int j : Comp[i]) cout<<j<<' ';
        cout<<'\n';
    }

    return 0;
}