#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <math.h>
#include <stack>
#include <deque>
#include <numeric>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <bitset>

#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const ld epsylon = 1e-9;
typedef unsigned int ui;

int main()
{
	freopen("lottery.in","r",stdin);
	freopen("lottery.out","w",stdout);
	int n;
	scanf("%d",&n);
	int u,v;
	vector<pair<int, int> > inp;
	for (int i = 0; i < n; ++i) {		
		scanf("%d %d", &u,&v);
		inp.push_back(make_pair(u,v));
	}
	vector<int> res;
	vector<int> s;
	int vis1[401];
	memset(vis1,0,sizeof(vis1));
	for (int i = 0; i < n; ++i) {
		bool ok = true;
		int node = inp[i].first;
		if (vis1[node]) continue;
		for (int j = 0; j < n; ++j) {
			if (i==j) continue;
			if (inp[j].second == node) {
				ok = false;
				break;
			}
		}
		if (ok) {
			vis1[node]=true;
			s.push_back(node);
		}
	}
	bool vis[1303];
	memset(vis,0,sizeof(vis));
	while (s.size() > 0) {
		int node = s[s.size()-1];
		s.pop_back();
		res.push_back(node);
		for (int i = 0; i < n; ++i) {
			if (vis[i]) continue;			
			if (inp[i].first == node) {
				vis[i] = true;
				bool ok = true;
				for (int j = 0; j < n; ++j) {
					if (!vis[j] && 
						inp[j].second == inp[i].second) {
							ok = false;
							break;
					}
				}
				if (ok) {
					s.push_back(inp[i].second);
				}
			}
		}
	}
	for (int i = 0; i < res.size(); ++i) {
		printf("%d%c",res[i],
			i<res.size()-1?' ':'\n');
	}
	return 0;
}