xcvxcv

#include <bits/stdc++.h>
using namespace std;
#define test int t; cin>>t; while (t--)
#define ll long long int
#define fellow_junior  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int main()
{
   fellow_junior
   ll t;
   while(cin>>t && t)
   {
       string a[1000];
       for(ll i=0;i<t;i++)
       {
           cin>>a[i];
       }
       sort(a,a+t);
       for(ll i=t-1;i>=0;i--)
       {
           cout<<a[i];
       }
       cout<<endl;
   }
   return 0;
}