#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int main() {
  int N; cin >> N;
  map<string, int> mp;
  for (int i = 0; i < N; i++) {
    string s; cin >> s;
    mp[s]++;
  }
  for (int i = 0; i < N - 1; i++) {
    string s; cin >> s;
    mp[s]--;
  }
  for (auto p: mp) {
    if (p.second > 0) {
      cout << p.first << endl;
      return 0;
    }
  }
  return 0;
}