#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <cctype>
#include <ctime>
#include <set>
#include <string>
#include <map>
using namespace std;
int n, n2;
string str;
set <string> s;
map <string, int> m;
int main() {
cin >> n;
n2 = n;
while(n--){
cin >> str;
s.insert(str);
m[str]++;
}
/*for (set <string> :: iterator it = s.begin(); it != s.end(); it++){
cout << *it << " " << m[*it] << endl;
}
cout << endl;*/
for (int i = 0; i < n2 - 1; i++){
cin >> str;
if (m[str] > 1) m[str]--;
else s.erase(str);
/*for (set <string> :: iterator it = s.begin(); it != s.end(); it++){
cout << *it << " " << m[*it] << endl;
}
cout << endl;*/
}
cout << *s.begin();
return 0;
}
