#include <bits/stdc++.h>
using namespace std;
#define ll long long
const ll inf=1e9;
const int maxn=100;
const ll mod=1e9+7;
map <string,int> used;
void solve(){
int a;
cin>>a;
vector <string> b(a);
for(int i=0;i<a;i++){
cin>>b[i];
}
for(int i=1;i<a;i++){
string s;
cin>>s;
used[s]++;
}
string ans="";
for(int i=0;i<a;i++){
if(used[b[i]]==0){
cout<<b[i];
return ;
}
used[b[i]]--;
}
}
int main(){
//ios_base::sync_with_stdio(false);
//cin.tie(NULL);
int t=1;
//cin>>t;
while(t--){
solve();
cout<<'\n';
}
}
