#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>



using namespace std;

const char iname[] = "ctc.in";
const char oname[] = "ctc.out";



vector <int> Go[100005], Gi[100005], G[100005];

void read_in(vector <int>* Go, vector <int>* Gi, int& n, const char iname[])
{
    ifstream in(iname);
    int cnt_edges, x, y;

    in >> n;
    for (in >> cnt_edges; cnt_edges > 0; -- cnt_edges) {
        in >> x >> y;
        x --, y --;
        Go[x].push_back(y);
        Gi[y].push_back(x);
    }
    in.close();
}

vector <int> discovered, used;

void DFP(const int n, vector <int>* G)
{
    vector <int>::iterator it;
    used[n] = true;
    for (it = G[n].begin(); it != G[n].end(); ++ it)
        if (used[*it] == false)
            DFP(*it, G);
    discovered.push_back(n);
}

vector <int> where;

void DFM(const int n, vector <int>* G, const int which)
{
    vector <int>::iterator it;
    where[n] = which;
    for (it = G[n].begin(); it != G[n].end(); ++ it)
        if (where[*it] == -1)
            DFM(*it, G, which);
}

void print_out(const vector <int>* G, const int n, const char oname[])
{
    ofstream out(oname);
    vector <int>::const_iterator it;

    out << n <<'\n';
    for (int i = 0; i < n; ++ i) {
        for (it = G[i].begin(); it != G[i].end(); ++ it)
            out << *it + 1 << " ";
        out << '\n';
    }
    out.close();
}

int main(void)
{
    int n;
    read_in(Go, Gi, n, iname);
    used.resize(n);
    used.assign(used.size(), 0);
    for (int i = 0; i < n; ++ i) if (used[i] == false)
            DFP(i, Go);
    where.resize(n);
    where.assign(where.size(), -1);
    int count = 0;
    for (; discovered.size(); discovered.pop_back())
        if (where[discovered.back()] == -1) {
            DFM(discovered.back(), Gi, count);
            count ++;
        }
    for (int i = 0; i < n; ++ i)
        G[where[i]].push_back(i);
    print_out(G, count, oname);
    return 0;
}