#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#define maxn 201
using namespace std;
struct edge{
	int ch[maxn],j;
};
edge haha[1010];
bool comp(const edge &a,const edge &b){
	for(int i=0;i<maxn;i++){
		if(a.ch[i]!=b.ch[i])
		return a.ch[i]>b.ch[i];
	}
}
int main(){
	freopen("brick.in","r",stdin); 
	freopen("brick.out","w",stdout);
	int n;
	cin>>n;
	cin.get();
	memset(haha,0,sizeof(haha));
	for(int i=0;i<n;i++){
		string s;
		getline(cin,s);
		//cout<<s<<endl;
		haha[i].j=s.size();
		for(int j=0;j<s.size();j++){
			haha[i].ch[j]=s[j]-'0';
		}
	}
	sort(haha,haha+n,comp);
	//cout<<n<<"hsbdh"<<endl;
	for(int i=0;i<n;i++){
		for(int j=0;j<haha[i].j;j++){
			cout<<haha[i].ch[j];
		}
	}
}