#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:134217728")
using namespace std;
template <class T>
T abs(T x) {
  return x > 0 ? x : -x;
}
int n;
map<int, int> m;
int p;
int add(int x) {
  if (!m.count(x)) m[x] = p++;
  return m[x];
}
vector<int> v[100500];
int val[100500];
void go(int x, int prev239) {
  cout << val[x];
  if (((int)(v[x]).size()) == 1) return;
  cout << ' ';
  if (v[x][0] == prev239)
    go(v[x][1], x);
  else
    go(v[x][0], x);
}
int main() {
  cin >> n;
  for (int i = 0; i < (n); i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    int p1 = add(a);
    int p2 = add(b);
    val[p1] = a;
    val[p2] = b;
    v[p1].push_back(p2);
    v[p2].push_back(p1);
  }
  for (int i = 0; i < (n); i++)
    if (((int)(v[i]).size()) == 1) {
      cout << val[i] << ' ';
      go(v[i][0], i);
      break;
    }
  cout << endl;
  return 0;
}
