#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define N 21
using namespace std;
int n;
string s[N];
bool cmp(string s1,string s2){return s1+s2>s2+s1;}
int main()
{
    scanf("%d",&n);
    for(int i=0;i<n;i++)cin>>s[i];
    sort(s,s+n,cmp);
    for(int i=0;i<n;i++)cout<<s[i];
    return 0;
}