#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define file freopen("in.txt", "r", stdin);
#define pii pair<int,int>
#define pb push_back
#define all(v) v.begin(), v.end()
#define keepunique(v) (v).erase(unique(all(v)),v.end())
#define fastread ios_base::sync_with_stdio(false);cin.tie(NULL);
map<string, int>mp;
int n;
string s[100005];
int main(){
//file
fastread
cin>>n;
for(int i=1; i<=n; i++){
cin>>s[i];
mp[s[i]]++;
}
for(int i=1; i<=n-1; i++){
string x;
cin>>x;
mp[x]++;
}
for(int i=1; i<=n; i++){
if(mp[s[i]]%2 != 0){
cout<<s[i]<<endl;
return 0;
}
}
}
