import java.io.InputStreamReader;
import java.io.PrintStream;
import java.io.StreamTokenizer;
import java.util.ArrayList;

public class Main {
    int n;
    ArrayList<ArrayList<Integer> > g = new ArrayList<ArrayList<Integer> > (), gInv = new ArrayList<ArrayList<Integer> > ();
    StreamTokenizer in = new StreamTokenizer(new InputStreamReader(System.in));
    PrintStream out = new PrintStream(System.out);
    ArrayList<Integer> topSort = new ArrayList<Integer> ();
    boolean[] used;
    int[] component;

    void init() {
        ArrayList<Integer> tmp = new ArrayList<Integer> ();
        for(int i = 0; i < n; i++) {
            g.add(tmp);
            gInv.add(tmp);
        }
        used = new boolean[n];
        component = new int[n];
    }

    Main()throws Exception{
        int m, x, y;

        in.nextToken();
        n = (int)in.nval;
        in.nextToken();
        m = in.nextToken();

        init();

        for(int i = 0; i< m; i++) {
            in.nextToken();
            x = (int)in.nval;
            in.nextToken();
            y = (int)in.nval;
            g.get(x).add(y);
            gInv.get(y).add(x);
        }
         for(int i = 0; i < n; i++) {
             if(!used[i]) {
                 top(i);
             }
         }

    }

    void top(int v) {
        used[v] = true;
        for(int i = 0; i < g.get(v).size(); i++) {
            if(!used[g.get(v).get(i)]) {
                top(g.get(v).get(i));
            }
        }
        topSort.add(v);
    }

    public static void main(String[] args) throws Exception {
        //Scanner in = new Scanner(System.in);
        new Main();
    }


}