#include <bits/stdc++.h> 
using namespace std;
 
string s[110]; 
 
//按字典码降序
bool cmp(string s1,string s2){
    //s1必须在前面 
    if(s1 + s2 > s2 + s1){
        return true;
    }else{
        return false;
    }
     
} 
 
int main(){
    int i,n,j;
    cin>>n;
    getchar();
    for(i = 0;i < n;i++){
        cin>>s[i];
    }
     
    sort(s,s+n,cmp);
    for(i = 0;i < n;i++){
        cout<<s[i];
    }
}
/**************************************************************
	Problem: 1505
	User: admin
	Language: C++
	Result: Accepted
	Time:31 ms
	Memory:2088 kb
****************************************************************/