#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  unordered_map<string, int> pastel;
  
  for (int i = 0; i < N * 2 - 1; i++) {
    string S = "";
    cin >> S;
    
    if (pastel.count(S))
      pastel[S]++;
    else
      pastel[S] = 1;
  }
  
  for (pair<string, int> p : pastel) {
    if (p.second % 2)
      cout << p.first << endl;
  }
}