#include <iostream>
#include <set>
#include <string>
using namespace std;

struct cmp{
	bool operator()(const string& a, const string& b){
		return a + b > b + a;
	}
};

int main(){
	set<string, cmp> a;
	int n;
	cin >> n;
	string tmp;
	for(int i = 0;i < n; i++){
		cin >> tmp;
		a.emplace(tmp);
	}
	for(string x : a){
		cout << x ;
	}
	cout << endl;
	return 0;
}