#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using pii = pair<int, int>;

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