#include "bits/stdc++.h"
#define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll long long
#define pb push_back
#define in insert
#define F first
#define S second
#define vll vector<ll>
#define all(v) v.begin(), v.end()
#define rep(a, b, c) for (int(a) = (b); (a) < (c); (a)++) // i, 0, n
#define endl '\n'
#define pii pair<ll,ll>
#define yes cout << "Yes" << endl;
#define no cout << "No" << endl;
using namespace std;
const ll INF = 1e18, mod = 1e9 + 7, N = 1e5 + 5;
ll gcd(ll a, ll b) {
return b == 0 ? a : gcd(b, a % b);
}
ll lcm(ll a, ll b) {
return (a / gcd(a, b)) * b;
}
ll modpow(ll a, ll b) {
ll ans = 1;
while(b > 0) {
if(b % 2 == 1) {
ans *= a;
ans %= mod;
}
a *= a;
a %= mod;
b >>= 1;
}
return ans % mod;
}
ll inv(ll a) {
return modpow(a, mod-2) % mod;
}
void solve(){
ll n;
cin >> n;
string s;
unordered_map<string ,ll>mp;
set<string>st;
for(int i = 0; i < 2 * n - 1; i++){
cin >> s;
mp[s]++;
}
for(auto i : mp){
if(i.S == 1){
cout << i.F << endl;
return;
}
}
}
int main() {
fast;
ll t = 1;
// cin >> t;
while(t--){
solve();
}
}
