#include <bits/stdc++.h>
using namespace std;
int main() {
    int n; cin >> n;
    vector<string> a(n);
    map<string,int> b;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        sort(a[i].begin(), a[i].end());
        b[a[i]]++;
    }
    for (auto x : b) {
        if (x.second % 2 == 1) {
            cout << x.first;
            return 0;
        }
    }
}