#include <bits/stdc++.h>

#define mp       make_pair
#define mt	 make_tuple
#define pb       push_back
#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    pair<int,int>      pii;
typedef    pair<long,long>    pll;

const int INF=1<<29;
const double EPS=1e-9;
const int MOD = 100000007;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
int N;
vector<string> S;
bool compare(const string &tmp1, const string &tmp2, int pos){
  if (pos >= tmp1.size()){
    return false;
  }
  if (pos >= tmp2.size()){
    return true;
  }
  if (tmp1[pos] == tmp2[pos]){
    return compare(tmp1, tmp2, pos + 1);
  }
  return tmp1[pos] < tmp2[pos];
}
int calc(){
  string tmp = S[0];
  int index = 0;
  for (int i = 1; i < S.size(); i++){
    if (compare(S[i], tmp, 0)){
      tmp = S[i];
      index = i;
    }
  }
  return index;
}

int main(){
  cin >> N;
  S.resize(N);
  for (int i = 0; i < N; i++){
    cin >> S[i];
  }
  string res = "";
  while (true){
    int index = calc();
    if (S[index].size() == 1){
      res += S[index][0];
      S.erase(S.begin() + index);
    }else{
      res += S[index][0];
      string tmp = S[index].substr(1);
      S.erase(S.begin() + index);
      S.push_back(tmp);
    }
    if (S.size() == 0)break;
  }
  cout << res << endl;
}