#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>

using namespace std;

vector<vector<int>> adj;
vector<bool> visited;
void dfs(int u){
    visited[u] = true;
    cout << u << " ";
    for(int v : adj[u]){
        if(!visited[v]){
            dfs(v);
        }
    }
}

int main() {
    int n, m;
    cin >> n >> m;
    adj.resize(n);
    visited.resize(n);
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
    }
    for(int i = 0; i < n; i++) {
        sort(adj[i].begin(), adj[i].end());
    }
    dfs(0);

    for(int i = 0; i < n; i++) {
        if(!visited[i]) {
            dfs(i);
        }
    }
    return 0;
}