{

bool operator()(const int &a, const int &b) const

{

return a > b;

}

{

vector<int> indegree(V+1, 0);

priority_queue<int, vector<int>, option> zero_indegree;

for (int u = 0; u < V; u++)

{

vector<int>::iterator it;

for (it = graph[u].begin(); it != graph[u].end(); it++)

indegree[*it]++;

}

for (int i = 0; i < V; i++)

if (indegree[i] == 0)

{

zero_indegree.push(i);

}

while (!zero_indegree.empty())

{

int u = zero_indegree.top();

zero_indegree.pop();

result.push_back(u);

vector<int>::iterator it;

for (it = graph[u].begin(); it != graph[u].end(); it++)

{

indegree[*it]--;

if (indegree[*it] == 0)

{

zero_indegree.push(*it);

}

}

}

for (int i = 0; i < V; i++)

{

if (indegree[i] != 0)

return false;

}

return true;

{

freopen("topologicalkahn.inp", "r", stdin);

freopen("topologicalkahn.out", "w", stdout);

vector<vector<int>> graph;

vector<int> result;

cin >> V >> E;

graph.assign(V + 1, vector<int>());

for (int u, v, i = 0; i < E; i++)

{

cin >> u >> v;

graph[u-1].push_back(v-1);

}

if (topologicalsort(graph, result) == true)

{

for (int i = 0; i < result.size(); i++)

cout << result[i]+1 << " ";

}

else

cout << "Sandro fails.";

}