#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <iomanip>
#include <vector>
#include <set>
#include <algorithm>
#define MAXN 0x7fffffff
using namespace std;
int a,b,c,d,r[10],l=0;
char ch[8][1000];
struct fun
{
	char cha[1000];
}f[40321];
bool bo[10];
int cmp ( const void *a , const void *b )
{
	struct fun *c = (struct fun *)a;
	struct fun *d = (struct fun *)b;
	return strcmp(c->cha,d->cha);
}
void DFS(int k)
{
	int i,j;
	if (k==a)
	{
		d=0;
		for (i=0;i<a;i++)
			for (j=0;j<strlen(ch[r[i]]);j++)
			{
				f[l].cha[d]=ch[r[i]][j];
				d++;
			}
		l++;
	}
	for (i=0;i<a;i++)
		if (bo[i]==false) 
		{
			r[k]=i;
			bo[i]=true;
			DFS(k+1);
			bo[i]=false;
		}
}
int main(void)
{
	freopen("substring.in","r",stdin);
	freopen("substring.out","w",stdout);
	scanf("%d",&a);
	for (b=0;b<a;b++) cin>>ch[b];
	DFS(0);
	qsort(f,l,sizeof(fun),cmp);
	cout<<f[0].cha;
	fclose(stdin);
	fclose(stdout);
	return 0;
}