#include <iostream>
#include <bits/stdc++.h>
#define INFILE "biconex.in"
#define OUTFILE "biconex.out"
#define RADACINA_FICTIVA -1
using namespace std;
typedef pair<int,int> edge;
ifstream in(INFILE);
ofstream out(OUTFILE);
int N,M;
vector<vector<int>> ComponenteBiconexe;
map<int,int> dnum;
map<int,int> low;
stack<edge> S;

void AddToCompBiconexe(int x,int y){
    vector<int> v;
    int tx,ty;
    do{
        tx=S.top().first;
        ty=S.top().second;
        v.push_back(tx),v.push_back(ty);
        S.pop();
    }while(tx!=x||ty!=y);
    ComponenteBiconexe.push_back(v);
}

struct Graph{
    int n;
    vector<vector<int>> Adj;
    void Init(int sz){
        n=sz;
        Adj.resize(n+1);
    }
    void Add(int x,int y){
        Adj[x].push_back(y);
        Adj[y].push_back(x);
    }
}G;

void Read(){
    in>>N>>M;
    G.Init(N);
    for(int i=1;i<=M;i++){
        int x,y;
        in>>x>>y;
       // cout<<x<<" "<<y<<endl;
        G.Add(x,y);
    }
}

void DFS(int x,int tx,int number){
    viz[x]=true;
    dnum[x]=low[x]=number;
    for(auto y:G.Adj[x]){
        if(y==tx) continue;
        if(dnum[y]==0){
            S.push(make_pair(x,y));
            DFS(y,x,number+1);
            low[x]=min(low[x],low[y]);
            if(low[y]>=dnum[x])
                AddToCompBiconexe(x,y);
        }
        else{
            low[x]=min(low[x],dnum[y]);
        }
    }
}

int main()
{
    Read();
    DFS(1,RADACINA_FICTIVA,1);
    out<<ComponenteBiconexe.size()<<"\n";
    for(auto c:ComponenteBiconexe){
        sort(c.begin(),c.end());
        c.erase(unique(c.begin(),c.end()),c.end());
        for(auto e:c){
            out<<e<<" ";
        }
        out<<"\n";
    }

    return 0;
}