#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;

bool cmp(string a, string b)
{
	int min_ = min(a.length(),b.length());
	for (int i = 0; i < min_; i++)
	{
		if (a[i]-'0' != b[i]-'0') return a[i]>b[i];
		else continue;
	}
	if (a[min_] < a[0])return a.length() < b.length();
	else return a.length() > b.length();
	if (b[min_] < b[0])return a.length() < b.length();
	else return a.length() > b.length();
}
int main()
{
	int n; cin >> n; vector<string> a(n);
	for (int i = 0; i < n; i++) cin >> a[i];
	sort(a.begin(), a.end(), cmp);
	for (string i : a)cout << i;

	return 0;
}