#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
int main() {
  int N; cin >> N;
  vector<string> A(N);
  vector<string> B(N - 1);
  for(int i = 0; i < N; i++) cin>> A[i];
  for(int i= 0; i < N - 1;i++) cin>> B[i];
  sort(A.begin(),A.end());
  sort(B.begin(),B.end());
  string ans = "";
  for(int i = 0; i < N - 1; i++) {
    if(A[i] != B[i]) {
      ans = A[i];
      break;
    }
  }
  if(ans == "") {
    cout << A[N -1] << endl;
    return 0;
  }
  cout << ans << endl;
}