#include <vector>
#include <algorithm>
#include <iostream>
#include <set>
#include <cmath>
#include <map>
#include <random>
#include <cassert>
#include <ctime>
#include <cstdlib>
#include <limits.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int N; cin >> N;
map<string,int> myMap;
for (int i = 0; i < N; i++) {
string x; cin >> x;
myMap[x]++;
}
for (int i = 0; i < N - 1; i++) {
string x; cin >> x;
myMap[x]--;
}
//cout << *(s.begin());
for (auto& p: myMap) {
if (p.second == 1) {
cout << p.first;
exit(0);
}
}
}
