#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <bitset>
#include<stack>
using namespace std;
///ifstream f ("dfs.in");ofstream g ("dfs.out");
///ifstream f("bfs.in");ofstream g("bfs.out");
///ifstream f("biconex.in");ofstream g("biconex.out");
ifstream f("ctc.in");ofstream g("ctc.out");
    int verif[100001],low[100001],cost[100001];
    vector <int> muchii[100001], componente[100001];
    vector<int> q[100001],w[100001],result[100001];
class graf{
private:
    int n, m, x, y, nods,counter=0, cont=0;

    queue <int> coada;

    vector<int> distanta{vector<int>(100001, -1)};
    stack<int>stiva;
public:
    graf(){}
    graf (int n, int m)  ///constructor graf dfs / biconexe
    {
        this-> n = n;
        this-> m = m;

        for(int i=1; i<=m; i++){
            f>>x>>y;
            muchii[x].push_back(y);
            muchii[y].push_back(x);
        }
    }
    graf(int n, int m, int nods){ /// constructor graf bfs
        this-> n = n;
        this-> m = m;
        this->nods=nods;
        for(int i=1;i<=m;i++){
            f>>x>>y;
            muchii[x].push_back(y);
        }
    }
    void citireCTC(int n, int m){
        this-> n = n;
        this-> m = m;
        for(int i=1; i<=m;i++) {
        int x,y;
        f>>x>>y;
        q[x].push_back(y);
        w[y].push_back(x);
        }
    }
    void dfs(int nod){    /// dfs simplu
        verif[nod]=true;
        for (int i=0; i<muchii[nod].size(); i++){
            int vecin = muchii[nod][i];
            if(verif[vecin]!=true)
                dfs(vecin);
        }
    }
    void bfs()   /// bfs simplu
    {
        int nod, vecin;
        while(!coada.empty())
        {
            nod=coada.front();
            coada.pop();
            for (int i= 0;i<muchii[nod].size();i++)
            {
                vecin = muchii[nod][i];
                if(distanta[vecin]==-1)
                {
                    coada.push(vecin);
                    distanta[vecin]=distanta[nod]+1;
                }
            }
        }
    }

    void dfsRez(){    /// rezolvare problema dfs
        for (int i=1;i<=n;i++){
            if (verif[i]!=true){
                counter++;
                dfs(i);
            }
        }
        g<<counter;
        }
    void bfsRez(){ /// rezolvare problema bfs
        distanta[nods]=0;
        coada.push(nods);
        bfs();
        for (int i=1;i<=n;i++){
            g<<distanta[i] <<" ";
        }

    }


void biconexe(int nod,int parent){ ///biconexe
verif[nod]=true;
low[nod]=cost[nod]=cost[parent]+1;
stiva.push(nod);
for (int i=0;i<muchii[nod].size();i++){
    if (muchii[nod][i] != parent){
        if (verif[muchii[nod][i]])
            low[nod]=min(low[nod],cost[muchii[nod][i]]);
        else{
            biconexe(muchii[nod][i],nod);
            low[nod]=min(low[nod],low[muchii[nod][i]]);
            if (low[muchii[nod][i]]>=cost[nod]){
                cont++;
                while (stiva.top()!=muchii[nod][i]){componente[cont].push_back(stiva.top());stiva.pop();}
                componente[cont].push_back(muchii[nod][i]);stiva.pop();componente[cont].push_back(nod);
            }
        }
    }
}
}

void biconexeRez(){ ///biconexe rezolvare
    for (int i=1;i<=n;i++)
        if (verif[i]==0)
            biconexe(i,0);
    g<<cont<<'\n';
    for (int i=1;i<=cont;i++){
        for (int j=componente[i].size()-1;j>=0;j--)
            g<< componente[i][j]<<" ";
        g<<'\n';
    }
}
void dq(int nod){
    verif[nod]=1;
    for(int i=0; i<q[nod].size();i++){
        int vecin=q[nod][i];
        if(verif[vecin]==false)
            dq(vecin);
    }
    stiva.push(nod);
}
void dw(int nod){
    verif[nod]=2;
    result[cont].push_back(nod);
    for(int i=0;i<w[nod].size();i++){
        int vecin=w[nod][i];
        if(verif[vecin]==1)
            dw(vecin);
    }
}
void ctcRez(){
for(int i=1; i<=n; i++)
    if(!verif[i])
        dq(i);

while(!stiva.empty()){
    int nod = stiva.top();
    if(verif[nod] == 1){
        cont++;
        dw(nod);
    }
    stiva.pop();
}
g<<cont<<'\n';
for(int i=1; i<=cont;i++){
    for(int j=0; j < result[i].size(); j++)
        g<<result[i][j]<<' ';
    g<<'\n';
}
}
virtual ~graf(){}
};
int main()
{
    /// int n,m;f>>n>>m;graf g1(n,m);g1.dfsRez();     ///dfs 100p
    /// int n,m,nods; f>>n>>m>>nods; graf g1(n,m,nods); g1.bfsRez(); ///bfs 100p
    ///int n,m;f>>n>>m;graf g1(n,m);g1.biconexeRez(); ///biconexe 100p
     int n,m;f>>n>>m;graf g1;g1.citireCTC(n,m);g1.ctcRez(); /// Componente tare conexe 100p
    return 0;
}