#include<iostream>
#include <list>
#include <stack>
#include<vector>
#include<algorithm>
#include<cstdio>
using namespace std;

// Class to represent a graph
class Graph
{
	int V;    // No. of vertices'

	list<int> *adj;

	// A function used by topologicalSort
	void topologicalSortUtil(int v, bool visited[], stack<int> &Stack);
public:
	Graph(int V);   // Constructor

	// function to add an edge to graph
	void addEdge(int v, int w);

	// prints a Topological Sort of the complete graph
	void topologicalSort();
};

Graph::Graph(int V)
{
	this->V = V;
	adj = new list<int>[V];
}

void Graph::addEdge(int v, int w)
{
	adj[v].push_back(w); // Add w to v’s list.
}

// A recursive function used by topologicalSort
void Graph::topologicalSortUtil(int v, bool visited[], stack<int> &Stack)
{
	// Mark the current node as visited.
	visited[v] = true;

	// Recur for all the vertices adjacent to this vertex
	list<int>::iterator i;
	for (i = adj[v].begin(); i != adj[v].end(); ++i)
	if (!visited[*i])
		topologicalSortUtil(*i, visited, Stack);

	// Push current vertex to stack which stores result
	Stack.push(v);
}

// The function to do Topological Sort. It uses recursive topologicalSortUtil()
void Graph::topologicalSort()
{
	stack<int> Stack;

	// Mark all the vertices as not visited
	bool *visited = new bool[V];
	for (int i = 0; i < V; i++)
		visited[i] = false;

	// Call the recursive helper function to store Topological Sort
	// starting from all vertices one by one
	for (int i = 0; i < V; i++)
	if (visited[i] == false)
		topologicalSortUtil(i, visited, Stack);

	// Print contents of stack
	while (Stack.empty() == false)
	{
		if (Stack.top() == 0){
			cout << V << " ";
		}
		else{
			cout << Stack.top() << " ";
		}
		Stack.pop();
	}
	cout<<endl;
}

// Driver program to test above functions
int main()
{
	// Create a graph given in the above diagram
	vector<pair<int, int> > rel;
    freopen("lottery.in", "r", stdin);
	freopen("lottery.out", "w", stdout);
	int countN, x, y, maxInd = 0;
	scanf("%d", &countN);
	for (int ind = 0; ind < countN; ind++){
		scanf("%d%d", &x, &y);
		maxInd = max(x, maxInd);
		maxInd = max(y, maxInd);
		pair<int, int> edge;
		edge.first = x;
		edge.second = y;
		rel.push_back(edge);
	}

	Graph g(maxInd);
	for (int ind = 0; ind < countN; ind++){
		g.addEdge(rel[ind].first, rel[ind].second);
	}

	g.topologicalSort();

	return 0;
}