/*
 * PA 2010
 * Laborator 7 - Aplicatii DFS
 *
 * Determinarea componentelor tare conexe
 *
 */

#include <cstdio> // daca vreti sa folositi printf, scanf
#include <iostream>
#include <fstream>
#include <vector>               
#include <stack>

using namespace std;

#define min(a, b) ((a) < (b) ? (a) : (b))
 
enum culoare_t {ALB, GRI, NEGRU};
typedef vector<int> *graf_t; 
 
int n, m;
graf_t G; // lista de adiacents
stack<int> S;

// Pentru retinerea solutiei si afisarea ei la sfarsit
vector <vector<int> > sol;
vector<int> crtcomp;

// In plus pentru Kosaraju
culoare_t *cul;
graf_t GT; // Lista de adiacenta a grafului transpus


void read_data(const char *filename)
{
	ifstream fin;
	int x, y;
	fin.open(filename);
	fin >> n >> m;
	G = new vector<int>[n];
	GT = new vector<int>[n]; // doar pentru Kosaraju
	for (int i = 0; i < m; i++)
	{
		fin >> x >> y;
		x--; y--; // indexare de la 0
		G[x].push_back(y);
		GT[y].push_back(x);
	}
}

/* Kosaraju */
void dfs(int v, graf_t lst)
{
	cul[v] = GRI;
	for (int i = 0; i < lst[v].size(); i++)
	{
		int u = lst[v][i];
	    	if (cul[u] == ALB)
			dfs(u, lst);
	}
	cul[v] = NEGRU;
	S.push(v);
}                      

void dfsT(int v, graf_t lst)
{
	cul[v] = GRI;
	crtcomp.push_back(v);

	// TODO: adaugare nod la noua componenta conexa (afisare)
	
	for (int i = 0; i < lst[v].size(); i++)
	{
		int u = lst[v][i];
	    	if (cul[u] == ALB)
			dfsT(u, lst);
	}
	cul[v] = NEGRU;

}                      

void ctc_kosaraju()
{
	// Alocari memorie
	cul = new culoare_t[n];
	
	int u, element;
	for(u = 0; u < n; u++)
		cul[u] = ALB;
	
	for(u = 0; u < n; u++)
		if(cul[u] == ALB)
			dfs(u, G);

	for(u = 0; u < n; u++)
		cul[u] = ALB;
	
	while(!S.empty())
	{
		element = S.top();
		S.pop();
		cout<<element;
		if(cul[element] == ALB)
		{
			dfsT(element, GT);
			sol.push_back(crtcomp);
			crtcomp.resize(0);
		}
	}
			
	// Dezalocari memorie
	delete[] cul;
}

// Afiseaza solutia daca a fost retinuta in "sol"
// (+ exemplu folosire iteratori)
void print_sol(const char *filename)
{
	ofstream fout;
	fout.open(filename);
	fout << sol.size() << endl;
	vector<vector<int> >::iterator s;

	for (s = sol.begin(); s != sol.end(); s++)
	{
		vector<int>::iterator v;
		for (v = s->begin(); v != s->end(); v++)
			fout << *v + 1 << " ";
		fout << endl;
	}
	fout.close();
}

void free_data()
{
	delete[] G;
	delete[] GT; // doar pentru Kosaraju
}

int main(int argc, char *argv[])
{   
    if (argc >= 2)
		read_data(argv[2]);
	else
		read_data("ctc.in");
	
	// TODO: implementare ctc_kosaraju sau ctc_tarjan
	ctc_kosaraju();
	// ctc_tarjan();
	
	if (argc >= 3)
		print_sol(argv[3]);
	else
		print_sol("ctc.out");

	free_data();

	return 0;
}