#include <bits/stdc++.h>
using namespace std;
 
vector<int> topo(vector<vector<int>> &adj){
    vector<int> indegree(adj.size(), 0);
 
    for (int i = 0; i < (int)adj.size(); i++) {
        for (auto j : adj[i]) {
            indegree[j]++;
        }
    }
 
    priority_queue<int, vector<int>, greater<int>> ready;
    for (int i = 0; i < (int)adj.size(); i++) {
        if (indegree[i] == 0) {
            ready.push(i);
        }
    }
 
    vector<int> topo_sort;
    while (!ready.empty()) {
        int node = ready.top();
        ready.pop();
        topo_sort.push_back(node);
 
        for (auto i : adj[node]) {
            indegree[i]--;
            if (indegree[i] == 0) {
                ready.push(i);
            }
        }
    }
 
    return topo_sort;
}
 
void solve() {
    int n, e;
    cin >> n >> e;
    vector<vector<int>> adj(n+1);
 
    for (int i = 0; i < e; i++) {
        int from, to;
        cin >> from >> to;
        adj[from].push_back(to);
    }
 
    vector<int> ans = topo(adj);
 
    if (ans.size() != n+1) {
        cout << "The graph has a cycle\n";
        return;
    }
 
    for (int i = 0; i <(int) ans.size(); i++) {
        cout << ans[i];
        if (i != ans.size() - 1) {
            cout << "->";
        }
    }
    cout << "\n";
}
 
int main() {
    solve();
    return 0;
}

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