#include <list>
#include <stack>
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

class Graph
{
	int N; // nr varfuri
	int M; //nr muchii

	// listele de adiacenta
	list<int>* adj;

	// folosita de sortare topologica pt rezultat
	void topological_sort_bfs(int v, bool visited[], stack<int>& Stack);
public:
	Graph(string file_name);
	void topological_sort();
};

Graph::Graph(string file_name)
{


	ifstream graph_file;
	graph_file.open(file_name);
	graph_file >> N >> M;
	//cout << N << M << endl;

	adj = new list<int>[N];
	int v, w;
	while (graph_file >> v >> w)
	{
		adj[v].push_back(w);
		//cout << v << w << endl;
	}
}


// functia recursiva folosita de topological sort
void Graph::topological_sort_bfs(int v, bool visited[], stack<int>& Stack)
{
	// varful curent il marcam ca vizitat
	visited[v] = true;

	// recurenta pt toate varfurile adiacente varfului curent v
	list<int>::iterator it;

	for (it = adj[v].begin(); it != adj[v].end(); ++it)
		if (!visited[*it])
		{
			//cout << "test"<<*it<<endl;
			topological_sort_bfs(*it, visited, Stack);
		}
	//stack salveaza rezultatul
	Stack.push(v);
	//cout << v<<endl;
}


void Graph::topological_sort()
{
	stack<int> Stack;

	// toate varfurile sunt nevizitate
	bool* visited = new bool[N];
	for (int i = 0; i < N; i++)
		visited[i] = false;

	// pt fiecare varf apelam functia recursiva
	for (int i = 0; i < N; i++)
		if (visited[i] == false)
		{
			//cout << i << endl;
			topological_sort_bfs(i, visited, Stack);

		}

	ofstream out_file;
	out_file.open("sortaret.out");
	while (Stack.empty() == false)
	{

		out_file << Stack.top() << " ";
		Stack.pop();
	}
}


int main()
{

	Graph g("sortaret.in");
	g.topological_sort();

	return 0;
}