#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
ifstream fin("sortaret.in");
ofstream fout("sortaret.out");

int n, m, v[50005], k;
vector<int> gr[50005];
bool viz[50005];

void citire() {
  fin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int x, y;
    fin >> x >> y;
    gr[x].push_back(y);
  }
}

void DFS(int x) {
  viz[x] = true;
  for (int i = 0; i < gr[x].size(); i++) {
    if (!viz[gr[x][i]]) {
      v[k++] = gr[x][i];
      DFS(gr[x][i]);
    }
  }
}

void parcComp() {
  for (int i = 1; i <= n; i++)
    if (!viz[i])
      DFS(i);
}

int main(int argc, const char * argv[]) {
  citire();
  parcComp();
  fout << v[0] - 1 << " ";
  for (int i = 0; i < k; i++)
    fout << v[i] << " ";
}