// Created by Armin on 2/14/2025.

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pp = pair<int, int>;
using vi = vector<int>;
using v = vector<int>;
using vvi = vector<vector<int>>;
using vpi = vector<pair<int, int>>;
using vl = vector<ll>;
using vs = vector<string>;
using ss = set<string>;
using msi = map<string, int>;
constexpr ll MOD = 1e9 + 7;

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);
    
    int n; cin >> n;
    msi m;
    for (int i = 0; i < n; i++) {
      string s; cin >> s;
      sort(s.begin(), s.end());
      m[s]++;
    }

    for (auto& [k, v] : m) {
      if (v % 2 == 1) {
        cout << k << '\n'; return 0;
      }
    }
    
    return 0;
}