include <bits/stdc++.h>

using namespace std; string s[25]; int n;

bool cmp(string a, string b) {

return a + b > b + a;

}

int main() {

cin >> n;
for (int i = 1; i <= n; i++)
	cin >> s[i];
sort(s + 1, s + 1 + n, cmp);
for (int i = 1; i <= n; i++)
	cout << s[i];
return 0;

}