#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
using namespace std;
typedef pair <int, int> pii;
typedef long long ll;
const int inf = 1e9 + 1;
const double eps = 1e-9;
const int MAXN = 1e5 + 1;
int n;
map <string, int> m;
string ime;
int main(){
cin >> n;
for (int i = 0; i < n; i++){
cin >> ime;
m[ime]++;
}
for (int i = 1; i < n; i++){
cin >> ime;
m[ime]--;
}
for (map<string,int>::iterator it = m.begin(); it != m.end(); it++){
if (it->second == 1){
cout << it->first;
return 0;
}
}
}
