// Source: https://usaco.guide/general/io

#include <bits/stdc++.h>
#include <vector>
using namespace std;

int main() {
	int n;
	cin >> n;
	map<string, int> a;
	for (int i = 0; i < n; i++) {
		string s;
		cin >> s;
		sort(s.begin(), s.end());
		a[s]++;
	}

	for (pair<string, int> p : a) {
		if (p.second % 2 == 1) cout << p.first;
	}
}