#include <bits/stdc++.h>
using namespace std;
const long long linf = 1e18 + 5;
const int mod = (int)1e9 + 7;
const int inf = 1e9;
const int N = 1e6 + 5;
long long fpow(long long base, long long power) {
  long long result = 1;
  while (power > 0) {
    if (power % 2 == 1) {
      result = (result * base);
    }
    base = (base * base);
    power /= 2;
  }
  return result;
}
long long a[1000010];
int main() {
  long long n;
  cin >> n;
  map<long long, long long> l, r;
  set<long long> le, ri;
  long long x, y, i;
  for (i = 1; i <= n; i++) {
    cin >> x >> y;
    l[y] = x;
    r[x] = y;
    le.insert(x);
    ri.insert(y);
  }
  for (set<long long>::iterator it = le.begin(); it != le.end(); it++) {
    if (ri.find(*it) == ri.end()) a[1] = *it;
  }
  for (i = 3; i <= n; i += 2) {
    a[i] = r[a[i - 2]];
  }
  a[2] = r[0];
  for (i = 2; i <= n; i += 2) {
    a[i + 2] = r[a[i]];
  }
  for (i = 1; i <= n; i++) {
    cout << a[i] << " ";
  }
  return 0;
}
