http://oj.tsinsen.com/A1118###
#include "bits/stdc++.h"
using namespace std;
bool f(string & a, string & b) {
return a + b > b + a;
}
int main() {
int n; cin >> n;
string s[25];
for (int i = 0; i < n; ++i)
cin >> s[i];
sort(s, s + n, f);
for (int i = 0; i < n; ++i)
cout << s[i];
return 0;
}