#include <fstream>
#include <set>
#include <stack>
#include <vector>
using namespace std;
ifstream cin("biconex.in");
ofstream cout("biconex.out");
int n, m, comp, x, y, root, id, copii, C;
stack<pair<int, int>>S;
vector<int> L[100002];
set<int>cb[100002];
int niv[100002], low[100002], viz[100002];
set<int>s;
void dfs(int nod){
    viz[nod]=1;
    low[nod]=niv[nod];
    id=min(id, nod);
    for(int i=0;i<L[nod].size();i++){
        int vecin=L[nod][i];
        if(viz[vecin]){
            low[nod]=min(low[nod], niv[vecin]);
        }
        else{
            S.push({nod, vecin});
            niv[vecin]=niv[nod]+1;
            dfs(vecin);
            low[nod]=min(low[nod], low[vecin]);
            if(nod==root)
                copii++;
            if(low[vecin]>=niv[nod]){
                ++C;
                while(1){
                    pair<int, int> p=S.top();
                    cb[C].insert(p.first);
                    cb[C].insert(p.second);
                    S.pop();
                    if(p.first==nod && p.second==vecin){
                        break;
                    }

                }
            }
        }
    }
}
int main() {
    cin>>n>>m;
    for(int i=1;i<=m;i++){
        cin>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    for(int i=1;i<=n;i++){
        if(!viz[i]){
            comp++;
            niv[i]=1;
            root=i;
            dfs(i);
        }
    }
    cout<<C<<"\n";
    for(int i=1;i<=C;i++){
        for(auto it:cb[i]){
            cout<<it<<" ";
        }
        cout<<"\n";
    }
}