#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<ll, ll> pii;
typedef pair<ld, ld> pld;
int n;
map<string, int> mpp;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
cin >> n;
string s;
for(int i = 0; i < n; ++i){
cin >> s;
++mpp[s];
}
for(int i = 1; i < n; ++i){
cin >> s;
++mpp[s];
}
for(auto u : mpp){
if(u.ss%2 == 1){
cout << u.ff << "\n";
return 0;
}
}
}
