#include<iostream>
#include<set>
#include<algorithm>
using namespace std;

int main(){
    int n;
    cin >> n;
    string s;
    multiset<string> ms;

    for(int i = 0; i < n; i++){
        cin >> s;
        ms.insert(s);
    }

    string ret = "";
    while(ms.size()){
        set<string>::iterator it = ms.begin();
        string choose = *it;
        auto tmp = it;
        for(tmp++; tmp != ms.end();tmp++){
            if(choose[0] != (*tmp)[0])    break;
            string tmpc = choose, tmps = *tmp;
            reverse(tmpc.begin(), tmpc.end());
            reverse(tmps.begin(), tmps.end());
            if(tmps < tmpc){
                it = tmp;
            }
        }
        ret += choose[0];
        ms.erase(it);
        if(choose.size() > 1){
            choose = choose.substr(1);
            ms.insert(choose);
        }
    }

    cout << ret << endl;

    return 0;
}